On the polynomials which form an Appell sequence (I)

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T. Popoviciu, Asupra polinoamelor cari formează un şir Appell (I), Bull. Mathematique de la Soc. Roumaine des Sciences, 33/34 (1932), pp. 11-21 (in Romanian)

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Bulletin mathématique de la Société Roumaine des Sciences

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Societatea de Științe Matematice din România

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1932 b -Popoviciu- Bull. Math. Soc. Roum. Sci. - On polynomials forming an Appell series (II
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ON POLYNOMIALS WHICH FORM AN APPELL SEQUENCE 1 1 ^(1){ }^{1}1) by TIB. POPOVICIU

  1. In our first article published under this title we searched for the sequences of polynomials in x :
    (1)
    which verify the conditions
P 0 = 1 , P 1 , P n , P 0 = 1 , P 1 , P n , P_(0)=1,P_(1),dotsP_(n,dots)P_{0}=1, P_{1}, \ldots P_{n, \ldots}P0=1,P1,Pn,
(2) A n P n + B n P n 1 + C n P n 2 = 0 (2) A n P n + B n P n 1 + C n P n 2 = 0 {:(2)A_(n)P_(n)+B_(n)P_(n-1)+C_(n)P_(n-2)=0:}\begin{equation*} A_{n} P_{n}+B_{n} P_{n-1}+C_{n} P_{n-2}=0 \tag{2} \end{equation*}(2)AnPn+BnPn1+CnPn2=0
A n , B n , C n A n , B n , C n A_(n),B_(n),C_(n)\boldsymbol{A}_{n}, \boldsymbol{B}_{n}, \boldsymbol{C}_{n}An,Bn,Cnfinding polynomials in x degrees 0 , 1 , 2 0 , 1 , 2 0,1,20,1,20,1,2respectively.
In particular, we studied the case when A n 0 A n 0 A_(n)!=0A_{n} \neq 0An0for anything n n nnnand the case A n = 0 A n = 0 A_(n)=0\boldsymbol{A}_{n}=0An=0for anything n n nnnWe now propose to study the third case reported in the above-mentioned article, when some of the A n A n Year)\boldsymbol{A}_{n}Anare zero. We observe that it is sufficient to always assume C n 0 C n 0 C_(n)!=0C_{n} \neq 0Cn0, because if we had a con= ditic of the form C n 0 C n 0 C_(n)-=0\boldsymbol{C}_{n} \equiv 0Cn0, we have a particular case of the condition A n = 0 A n = 0 A_(n)=0\boldsymbol{A}_{n}=0An=0. It may happen that the relation (3) is not unique; we agree to say that A n 0 A n 0 A_(n)!=0\boldsymbol{A}_{n} \neq 0An0when there is no relationship (3) where A n = 0 A n = 0 A_(n)=0A_{n}=0An=0We saw in No. 3 of the previous article when this is possible.
We will use the notations from the previous article, to which the reader is asked to refer.
2. Suppose
A n + 1 = 0 A n + 1 = 0 A_(n+1)=0A_{n+1}=0An+1=0
It immediately follows that we can take
A n + 2 = A n + 3 = = A n = = 1 A n + 2 = A n + 3 = = A n = = 1 A_(n+2)=A_(n+3)=dots=A_(n)=dots=1A_{n+2}=A_{n+3}=\ldots=A_{n}=\ldots=1An+2=An+3==An==1
without losing the generality of the problem, because if A m = 0 A m = 0 A_(m)=0\boldsymbol{A}_{m}=0Am=0or we can
1 1 ^(1){ }^{1}1) Second note. function _ _ _ _ _ _ _ _ ____\_\_\_\_____
The recurrence formulas established in No. 4 of the previous article give us,
λ 2 = λ m m 1 λ m ( m 2 ) λ 2 = λ m m 1 λ m ( m 2 ) lambda_(2)=(lambda_(m))/(m-1-lambda_(m)(m-2))\lambda_{2}=\frac{\lambda_{m}}{m-1-\lambda_{m}(m-2)}λ2=λmm1λm(m2)
whatever it may be m 2 m 2 m >= 2m \geq 2m2. The equality immediately follows depending on λ n + 2 , μ n + 2 , n n + 2 , β n + 2 λ n + 2 , μ n + 2 , n n + 2 , β n + 2 lambda_(n+2),mu_(n+2),nu_(n+2),beta_(n+2)\lambda_{n+2}, \mu_{n+2}, \nu_{n+2}, \beta_{n+2}λn+2,μn+2,nn+2,βn+2, which is reduced
1 + λ n + 2 + A n + 2 = 0 1 + λ n + 2 + A n + 2 = 0 1+lambda_(n+2)+a_(n+2)=01+\lambda_{n+2}+a_{n+2}=01+λn+2+An+2=0
immediately results in equality
λ n + 2 n + 1 n λ n + 2 = λ m m 1 ( m 2 ) λ n λ n + 2 n + 1 n λ n + 2 = λ m m 1 ( m 2 ) λ n (lambda_(n+2))/(n+1-nlambda_(n+2))=(lambda_(m))/(m-1-(m-2)lambda_(n))\frac{\lambda_{n+2}}{n+1-n \lambda_{n+2}}=\frac{\lambda_{m}}{m-1-(m-2) \lambda_{n}}λn+2n+1nλn+2=λmm1(m2)λn
from which
(4) λ m = ( m 1 ) λ n + 2 n + 1 + ( m n 2 ) λ n + 2 (4) λ m = ( m 1 ) λ n + 2 n + 1 + ( m n 2 ) λ n + 2 {:(4)lambda_(m)=((m-1)lambda_(n+2))/(n+1+(mn-2)lambda_(n+2)):}\begin{equation*} \lambda_{m}=\frac{(m-1) \lambda_{n+2}}{n+1+(mn-2) \lambda_{n+2}} \tag{4} \end{equation*}(4)λm=(m1)λn+2n+1+(mn2)λn+2
FROM
λ m λ ^ n + 2 = μ m μ n + 2 = V m V n + 2 λ m λ ^ n + 2 = μ m μ n + 2 = V m V n + 2 (lambda_(m))/( hat(lambda)_(n+2))=(mu_(m))/(mu_(n)+2)=(v_(m))/(v_(n+2))\frac{\lambda_{m}}{\hat{\lambda}_{n+2}}=\frac{\mu_{m}}{\mu_{n}+2}=\frac{v_{m}}{v_{n+2}}λmλ^n+2=μmμn+2=VmVn+2
deduce
(5) μ m = ( m 1 ) μ n + 2 n + 1 + ( m n 2 ) λ n + 2 , V m = ( m 1 ) V ε + 2 n + 1 + ( m n 2 ) λ n + 2 (5) μ m = ( m 1 ) μ n + 2 n + 1 + ( m n 2 ) λ n + 2 , V m = ( m 1 ) V ε + 2 n + 1 + ( m n 2 ) λ n + 2 {:(5)mu_(m)=((m-1)mu_(n+2))/(n+1+(mn-2)lambda_(n+2))","v_(m)=((m-1)v_(epsilon+2))/(n+1+(mn-2)lambda_(n+2)):}\begin{equation*} \mu_{m}=\frac{(m-1) \mu_{n+2}}{n+1+(mn-2) \lambda_{n+2}}, v_{m}=\frac{(m-1) v_{\epsilon+2}}{n+1+(mn-2) \lambda_{n+2}} \tag{5} \end{equation*}(5)μm=(m1)μn+2n+1+(mn2)λn+2,Vm=(m1)Vε+2n+1+(mn2)λn+2
(6)
A m = n + 1 + ( 2 m n 3 ) λ n + 2 n + 1 + ( m n 2 ) λ n + 2 A m = n + 1 + ( 2 m n 3 ) λ n + 2 n + 1 + ( m n 2 ) λ n + 2 a_(m)=-(n+1+(2m-n-3)lambda_(n)+2)/(n+1+(mn-2)lambda_(n)+2)a_{m}=-\frac{n+1+(2 mn-3) \lambda_{n}+2}{n+1+(mn-2) \lambda_{n}+2}Am=n+1+(2mn3)λn+2n+1+(mn2)λn+2
We then have the recurrence relation: β m [ ( n + 1 ) + ( m n 2 ) λ n + 2 ] β m 1 | n + 1 + ( m n 3 ) λ n + 2 | + μ n + 2 = 0 β m ( n + 1 ) + ( m n 2 ) λ n + 2 β m 1 n + 1 + ( m n 3 ) λ n + 2 + μ n + 2 = 0 beta_(m)[(n+1)+(mn-2)lambda_(n+2)]-beta_(m-1)|n+1+(mn-3)lambda_(n+2)|+mu_(n+2)=0\beta_{m}\left[(n+1)+(mn-2) \lambda_{n+2}\right]-\beta_{m-1}\left|n+1+(mn-3) \lambda_{n+2}\right|+\mu_{n+2}=0βm[(n+1)+(mn2)λn+2]βm1|n+1+(mn3)λn+2|+μn+2=0from where
(7) β m = ( n + 1 ) β n + 2 ( m n 2 ) μ n + 2 n + 1 + ( m n 2 ) λ n + 2 (7) β m = ( n + 1 ) β n + 2 ( m n 2 ) μ n + 2 n + 1 + ( m n 2 ) λ n + 2 {:(7)beta_(m)=((n+1)beta_(n+2)-(mn-2)mu_(n+2))/(n+1+(mn-2)lambda_(n+2)):}\begin{equation*} \beta_{m}=\frac{(n+1) \beta_{n+2}-(mn-2) \mu_{n+2}}{n+1+(mn-2) \lambda_{n+2}} \tag{7} \end{equation*}(7)βm=(n+1)βn+2(mn2)μn+2n+1+(mn2)λn+2
To completely resolve the problem, it is necessary to determine λ m , μ m λ m , μ m lambda_(m),mu_(m)\lambda_{m}, \mu_{m}λm,μm, V m , p m , α m V m , p m , α m v_(m),p_(m),alpha_(m)v_{m}, p_{m}, \alpha_{m}Vm,pm,αmfor m n + 2 m n + 2 m <= n+2m \leq n+2mn+2.
But I saw that
P n = ( x + A ) k ( x + b ) n k P n = ( x + A ) k ( x + b ) n k P_(n)=(x+a)^(k)(x+b)^(nk)P_{n}=(\mathrm{x}+a)^{k}(\mathrm{x}+b)^{n-k}Pn=(x+A)k(x+b)nk
We can write for simplification
P n = r n k ( x + b 1 ) k P n = r n k x + b 1 k P_(n)=r^(n-k)(x+b_(1))^(k)P_{n}=\mathrm{r}^{n-k}\left(\mathrm{x}+b_{1}\right)^{k}Pn=Rnk(x+b1)k
and the general result will be obtained by substituting for x , b 1 , pc x + b , a b x , b 1 , pc x + b , a b x,b_(1),pcx+b,a-bx, b_{1}, \mathrm{pc} x+b, a-bx,b1,pcx+b,Abres= spectively. Nothing of generality is thus lost, for
d d ( x + b ) = d d x d d ( x + b ) = d d x (d)/(d(x+b))=(d)/(dx)\frac{d}{d(x+b)}=\frac{d}{d x}dd(x+b)=ddx
the character of the polynomials is therefore maintained by this simplification
3. Let k = 0 k = 0 k=0k=0k=0, so
P n = x n P n = x n P_(n)=x^(n)P_{n}=\mathrm{x}^{n}Pn=xn
polynomials P i , i < n P i , i < n P_(i,)i < n\boldsymbol{P}_{i,} \boldsymbol{i}<\boldsymbol{n}Pand,and<n, are determined, the constants λ m , μ m , ν m , α m , β m cu = λ m , μ m , ν m , α m , β m cu = lambda_(m),mu_(m),nu_(m),alpha_(m),beta_(m)cu=\lambda_{m}, \mu_{m}, \nu_{m}, \alpha_{m}, \beta_{m} \mathrm{cu}=λm,μm,nm,αm,βmwith=known for m n + 1 m n + 1 m <= n+1m \leq n+1mn+1.
Let's put
P n + 1 = x n + 1 + c , P n + 2 = x n + 2 + ( n + 2 ) c x + c 1 P n + 1 = x n + 1 + c , P n + 2 = x n + 2 + ( n + 2 ) c x + c 1 P_(n+1)=x^(n+1)+c,P_(n+2)=x^(n+2)+(n+2)cx+c_(1)P_{n+1}=\mathrm{x}^{n+1}+c, P_{n+2}=\mathrm{x}^{n+2}+(n+2) c \mathrm{x}+c_{1}Pn+1=xn+1+c,Pn+2=xn+2+(n+2)cx+c1
c. c 1 c 1 c_(1)\boldsymbol{c}_{1}c1being two constants. It is seen that to have an interesting case, irreducible to those studied so far, we must assume c 0 c 0 c!=0c \neq 0c0.
I have then
( n + 2 ) c x + c 1 + c B n + 2 = 0 x 2 + x B n + 2 + C + 2 = 0 ( n + 2 ) c x + c 1 + c B n + 2 = 0 x 2 + x B n + 2 + C + 2 = 0 {:[(n+2)cx+c_(1)+cB_(n+2)=0],[x^(2)+xB_(n+2)+C+2=0]:}\begin{gathered} (n+2) c \mathrm{x}+c_{1}+c B_{n+2}=0 \\ \mathrm{x}^{2}+\mathrm{x} B_{n+2}+C+2=0 \end{gathered}(n+2)cx+c1+cBn+2=0x2+xBn+2+C+2=0
and it is removed immediately
α n + 2 = ( n + 2 ) λ n + 2 = n + 1 β n + 2 = c 1 c = σ μ n + 2 = σ v n + 2 = 0 α n + 2 = ( n + 2 ) λ n + 2 = n + 1 β n + 2 = c 1 c = σ μ n + 2 = σ v n + 2 = 0 {:[alpha_(n+2)=-(n+2),lambda_(n+2)=n+1],[beta_(n+2)=-(c_(1))/(c)=sigma,mu_(n+2)=-sigma],[v_(n+2)=0]:}\begin{array}{ll} \alpha_{n+2}=-(n+2) & \lambda_{n+2}=n+1 \\ \beta_{n+2}=-\frac{c_{1}}{c}=\sigma & \mu_{n+2}=-\sigma \\ v_{n+2}=0 \end{array}αn+2=(n+2)λn+2=n+1βn+2=c1c=σμn+2=σVn+2=0
Formulas (4), (5), (6), (7) now give us pc λ m , μ m , ν m , α m , β m pc λ m , μ m , ν m , α m , β m pclambda_(m),mu_(m),nu_(m),alpha_(m),beta_(m)\mathrm{pc} \lambda_{m}, \mu_{m}, \nu_{m}, \alpha_{m}, \beta_{m}pcλm,μm,nm,αm,βmand all relations (3) are determined.
We can write in the above case
P m = x m + Q m n 1 P m = x m + Q m n 1 P_(m)=x^(m)+Q_(m-n-1)\boldsymbol{P}_{m}=\mathbf{x}^{m}+Q_{m-n-1}Pm=xm+Qmn1
where the sequence of polynomials
(8) Q 0 = c , Q 1 , Q 2 , Q s (8) Q 0 = c , Q 1 , Q 2 , Q s {:(8)Q_(0)=c","Q_(1)","Q_(2)","dotsQ_(s)dots:}\begin{equation*} Q_{0}=c, Q_{1}, Q_{2}, \ldots Q_{s} \ldots \tag{8} \end{equation*}(8)Q0=c,Q1,Q2,QS
check the relationships
(9) d Q m n 1 d x = m Q m n 2 Q m n 1 + B m Q m n 2 + C m Q m n 3 = 0 (9) d Q m n 1 d x = m Q m n 2 Q m n 1 + B m Q m n 2 + C m Q m n 3 = 0 {:[(9)(dQ_(m-n-1))/(dx)=mQ_(m-n-2)],[Q_(m-n-1)+B_(m)Q_(m-n-2)+C_(m)Q_(m-n-3)=0]:}\begin{gather*} \frac{d Q_{m-n-1}}{d \mathrm{x}}=m Q_{m-n-2} \tag{9}\\ Q_{m-n-1}+B_{m} Q_{m-n-2}+C_{m} Q_{m-n-3}=0 \end{gather*}(9)dQmn1dx=mQmn2Qmn1+BmQmn2+CmQmn3=0
So the sequence of polynomials:
(10) R 0 = c , R 1 , R s , (10) R 0 = c , R 1 , R s , {:(10)R_(0)=c","R_(1)","dotsR_(s)","dots:}\begin{equation*} R_{0}=c, R_{1}, \ldots R_{s}, \ldots \tag{10} \end{equation*}(10)R0=c,R1,RS,
where
Q s = ( n + s + 1 s ) R s Q s = ( n + s + 1 s ) R s Q_(s)=((n+s+1)/(s))R_(s)Q_{s}=\binom{n+s+1}{s} R_{s}QS=(n+S+1S)RS
is an APPELL string checking the condition:
(11) ( n + s + 1 s ) R s + ( n + s s 1 ) B n + s + 1 R s 1 ( n + s 1 s 2 ) ( n + s + 1 s ) R s + ( n + s s 1 ) B n + s + 1 R s 1 ( n + s 1 s 2 ) quad((n+s+1)/(s))R_(s)+((n+s)/(s-1))B_(n+s+1)R_(s-1)((n+s-1)/(s-2))\quad\binom{n+s+1}{s} R_{s}+\binom{n+s}{s-1} B_{n+s+1} R_{s-1}\binom{n+s-1}{s-2}(n+S+1S)RS+(n+SS1)Bn+S+1RS1(n+S1S2)
C n + s + 1 R s 2 = 0 C n + s + 1 R s 2 = 0 C_(n+s+1)R_(s-2)=0\boldsymbol{C}_{n+s+1} \boldsymbol{R}_{s-2}=0Cn+S+1RS2=0
And polynomials R s R s R_(s)\boldsymbol{R}_{s}RSfalls into the case studied in the previous chapter under No. 4.
But we have
B n + s + 1 = n + 2 s s × + σ ( n + s ) s ( n + 1 ) C n + s + 1 = n + s s x 2 σ ( n + s ) s ( n + 1 ) × B n + s + 1 = n + 2 s s × + σ ( n + s ) s ( n + 1 ) C n + s + 1 = n + s s x 2 σ ( n + s ) s ( n + 1 ) × {:[B_(n+s+1)=-(n+2s)/(s)xx+(sigma(n+s))/(s(n+1))],[C_(n+s+1)=(n+s)/(s)x^(2)-(sigma(n+s))/(s(n+1))xx]:}\begin{gathered} B_{n+s+1}=-\frac{n+2 s}{s} \times+\frac{\sigma(n+s)}{s(n+1)} \\ C_{n+s+1}=\frac{n+s}{s} x^{2}-\frac{\sigma(n+s)}{s(n+1)} \times \end{gathered}Bn+S+1=n+2SS×+σ(n+S)S(n+1)Cn+S+1=n+SSx2σ(n+S)S(n+1)×
(12) ( n + s + 1 ) R s + [ ( n + 2 s ) × + σ ( n + s ) n + 1 ] R s 1 + ( s 1 ) ( x 2 σ n + 1 × ) R s 2 = 0 (12) ( n + s + 1 ) R s + ( n + 2 s ) × + σ ( n + s ) n + 1 R s 1 + ( s 1 ) x 2 σ n + 1 × R s 2 = 0 {:[(12)(n+s+1)R_(s)+[-(n+2s)xx+(sigma(n+s))/(n+1)]],[R_(s-1)+(s-1)(x^(2)-(sigma)/(n+1)xx)R_(s-2)=0]:}\begin{align*} & (n+s+1) R_{s}+\left[-(n+2 s) \times+\frac{\sigma(n+s)}{n+1}\right] \tag{12}\\ & R_{s-1}+(s-1)\left(\mathrm{x}^{2}-\frac{\sigma}{n+1} \times\right) R_{s-2}=0 \end{align*}(12)(n+S+1)RS+[(n+2S)×+σ(n+S)n+1]RS1+(S1)(x2σn+1×)RS2=0
So we enter the general case by taking:
λ = 1 n + 3 , μ = σ ( n + 1 ) ( n + 3 ) , ν = 0 , β = σ ( n + 2 ) ( n + 1 ) ( n + 3 ) λ = 1 n + 3 , μ = σ ( n + 1 ) ( n + 3 ) , ν = 0 , β = σ ( n + 2 ) ( n + 1 ) ( n + 3 ) lambda=(1)/(n+3),mu=-(sigma)/((n+1)(n+3)),nu=0,beta=(sigma(n+2))/((n+1)(n+3))\lambda=\frac{1}{n+3}, \mu=-\frac{\sigma}{(n+1)(n+3)}, \nu=0, \beta=\frac{\sigma(n+2)}{(n+1)(n+3)}λ=1n+3,μ=σ(n+1)(n+3),n=0,β=σ(n+2)(n+1)(n+3)
It is then obtained
s = 0 7 s s ! R s = c e α x G . ( n + 1 , n + 2 , σ n + 1 z ) s = 0 7 s s ! R s = c e α x G . n + 1 , n + 2 , σ n + 1 z uuu_(s=0)^(oo)(7^(s))/(s!)R_(s)=c*e^(alpha x)quad G.(n+1,n+2,-(sigma)/(n+1)z)\bigcup_{s=0}^{\infty} \frac{\boldsymbol{7}^{s}}{\boldsymbol{s}!} \boldsymbol{R}_{s}=\boldsymbol{c} \cdot \boldsymbol{e}^{\alpha x} \quad G .\left(n+1, n+2,-\frac{\sigma}{n+1} \mathrm{z}\right)S=07SS!RS=cit isαxG.(n+1,n+2,σn+1z)
for R 0 = c R 0 = c R_(0)=c\boldsymbol{R}_{0}=\boldsymbol{c}R0=c,
s = 0 z n + s + 1 ( n + s + 1 ) ! Q s = z n + 1 ( n + 1 ) ! 0 z s s ! R s s = 0 z n + s + 1 ( n + s + 1 ) ! Q s = z n + 1 ( n + 1 ) ! 0 z s s ! R s sum_(s=0)^(oo)(z^(n+s+1))/((n+s+1)!)Q_(s)=(z^(n+1))/((n+1)!)sum_(0)^(oo)(z^(s))/(s!)R_(s)\sum_{s=0}^{\infty} \frac{z^{n+s+1}}{(n+s+1)!} Q_{s}=\frac{z^{n+1}}{(n+1)!} \sum_{0}^{\infty} \frac{z^{s}}{s!} R_{s}S=0zn+S+1(n+S+1)!QS=zn+1(n+1)!0zSS!RS
and so the generating function is
m = 0 z m m ! P m = e 2 x [ 1 + c z n + 1 ( n + 1 ) ! G ( n + 1 , n + 2 , σ n + 1 z ) ] m = 0 z m m ! P m = e 2 x 1 + c z n + 1 ( n + 1 ) ! G n + 1 , n + 2 , σ n + 1 z sum_(m=0)^(oo)(z^(m))/(m!)P_(m)=e^(2x)[1+c(z^(n+1))/((n+1)!)G(n+1,n+2,-(sigma)/(n+1)z)]\sum_{m=0}^{\infty} \frac{\mathbf{z}^{m}}{m!} \boldsymbol{P}_{m}=e^{2 x}\left[1+c \frac{\mathbf{z}^{n+1}}{(n+1)!} G\left(n+1, n+2,-\frac{\sigma}{n+1} z\right)\right]m=0zmm!Pm=it is2x[1+czn+1(n+1)!G(n+1,n+2,σn+1z)]
But it can be said for the general case
P n = ( x + b ) n P n = ( x + b ) n P_(n)=(x+b)^(n)P_{n}=(\mathrm{x}+b)^{n}Pn=(x+b)n
that polynomials are generated by the function
e ( x + b ) [ 1 + c z n + 1 ( n + 1 ) ! G ( n + 1 , n + 2 , θ z ) ] e ( x + b ) 1 + c z n + 1 ( n + 1 ) ! G ( n + 1 , n + 2 , θ z ) e^(ℓ(x+b))[1+c(z^(n+1))/((n+1)!)G(n+1,n+2,theta z)]e^{\ell(x+b)}\left[1+c \frac{z^{n+1}}{(n+1)!} G(n+1, n+2, \theta z)\right]it is(x+b)[1+czn+1(n+1)!G(n+1,n+2,θz)]
b , c , d b , c , d b,c,db, c, db,c,dbeing arbitrary constants.
The previous result was obtained under the assumption σ 0 σ 0 sigma!=0\sigma \neq 0σ0If
σ = 0 σ = 0 sigma=0\sigma=0σ=0The procedure we applied in the previous paper does not make sense, but it is easy to see that the formula remains applicable. We obtain the generating function
e z ( x + b ) [ 1 + c z n + 1 ( n + 1 ) ! ] e z ( x + b ) 1 + c z n + 1 ( n + 1 ) ! e^(z(x+b))[1+c(z^(n+1))/((n+1)!)]e^{z(x+b)}\left[1+c \frac{z^{n+1}}{(n+1)!}\right]it isz(x+b)[1+czn+1(n+1)!]
  1. Let's move on to the case. k = 1 k = 1 k=1k=1k=1, which is treated in the same way.
P n = x n 19 ( x + b 1 ) P n = x n 19 x + b 1 P_(n)=x^(n-19)(x+b_(1))P_{n}=\mathrm{x}^{n-19}\left(\mathrm{x}+b_{1}\right)Pn=xn19(x+b1)
P n + 1 = x n ( x + n + 1 n b 1 ) + c , P n + 2 = x n + 1 ( x + n + 2 n b 1 ) + ( n + 2 ) c x + c 1 P n + 1 = x n x + n + 1 n b 1 + c , P n + 2 = x n + 1 x + n + 2 n b 1 + ( n + 2 ) c x + c 1 P_(n+1)=x^(n)(x+(n+1)/(n)b_(1))+c,P_(n+2)=x^(n+1)(x+(n+2)/(n)b_(1))+(n+2)cx+c_(1)P_{n+1}=\mathrm{x}^{n}\left(\mathrm{x}+\frac{n+1}{n} b_{1}\right)+c, P_{n+2}=\mathrm{x}^{n+1}\left(\mathrm{x}+\frac{n+2}{n} b_{1}\right)+(n+2) c \mathrm{x}+c_{1}Pn+1=xn(x+n+1nb1)+c,Pn+2=xn+1(x+n+2nb1)+(n+2)cx+c1and c 0 c 0 c!=0\boldsymbol{c} \neq 0c0.
It is found that
α n + 2 = ( n + 2 ) β n + 2 = c 1 c = n b 1 α n + 2 = ( n + 2 ) β n + 2 = c 1 c = n b 1 {:[alpha_(n+2)=-(n+2)],[beta_(n+2)=-(c_(1))/(c)=-nb_(1)]:}\begin{aligned} & \alpha_{n+2}=-(n+2) \\ & \beta_{n+2}=-\frac{c_{1}}{c}=-n b_{1} \end{aligned}αn+2=(n+2)βn+2=c1c=nb1
We can also write here
P m = x m 1 ( x + m n b 1 ) + Q m n 1 P m = x m 1 x + m n b 1 + Q m n 1 P_(m)=x^(m-1)(x+(m)/(n)b_(1))+Q_(m-n-1)\boldsymbol{P}_{m}=\mathrm{x}^{m-1}\left(\mathrm{x}+\frac{m}{n} b_{1}\right)+Q_{m-n-1}Pm=xm1(x+mnb1)+Qmn1
and polynomials Q s Q s Q_(s)Q_{s}QSverify the relation (9). The polynomials are deduced R R R\boldsymbol{R}R, with relation (11), which is written
( n + s + 1 ) R s + [ ( n + 2 s ) × + ( 1 n s ) b 1 ] R s 1 + ( s 1 ) ( x 2 + b x ) R s 2 = 0 ( n + s + 1 ) R s + ( n + 2 s ) × + ( 1 n s ) b 1 R s 1 + ( s 1 ) x 2 + b x R s 2 = 0 {:[(n+s+1)R_(s)+[-(n+2s)xx+(1-n-s)b_(1)]],[R_(s-1)+(s-1)(x^(2)+b_(x))R_(s-2)=0]:}\begin{gathered} (n+s+1) R_{s}+\left[-(n+2 s) \times+(1-n-s) b_{1}\right] \\ R_{s-1}+(s-1)\left(\mathrm{x}^{2}+b_{x}\right) R_{s-2}=0 \end{gathered}(n+S+1)RS+[(n+2S)×+(1nS)b1]RS1+(S1)(x2+bx)RS2=0
and it can be taken
λ = 1 n + 3 , μ = b 1 n + 3 , ν = 0 , β = n + 1 n + 3 b 1 λ = 1 n + 3 , μ = b 1 n + 3 , ν = 0 , β = n + 1 n + 3 b 1 lambda=(1)/(n+3),mu=(b_(1))/(n+3),nu=0,beta=-(n+1)/(n+3)b_(1)\lambda=\frac{1}{n+3}, \mu=\frac{b_{1}}{n+3}, \nu=0, \beta=-\frac{n+1}{n+3} b_{1}λ=1n+3,μ=b1n+3,n=0,β=n+1n+3b1
and the generating function is:
0 z s s ! R s = c e 2 x G ( n , n + 2 , b 1 z ) 0 z s s ! R s = c e 2 x G n , n + 2 , b 1 z sum_(0)^(oo)(z^(s))/(s!)R_(s)=c*e^(2x)G(n,n+2,b_(1)z)\sum_{0}^{\infty} \frac{\mathbf{z}^{s}}{\boldsymbol{s}!} \boldsymbol{R}_{s}=\boldsymbol{c} \cdot \boldsymbol{e}^{2 x} \boldsymbol{G}\left(\boldsymbol{n}, \boldsymbol{n}+2, b_{1} \mathbf{z}\right)0zSS!RS=cit is2xG(n,n+2,b1z)
For the general case we have immediately:
0 z m m ! P m = e z ( x + b ) [ 1 + 2 n ( a b ) z + c G ( n , n + 2 ( a b ) z ) ] 0 z m m ! P m = e z ( x + b ) 1 + 2 n ( a b ) z + c G ( n , n + 2 ( a b ) z ) sum_(0)^(oo)(z^(m))/(m!)P_(m)=e^(z(x+b))[1+(2)/(n)(a-b)z+cG(n,n+2(a-b)z)]\sum_{0}^{\infty} \frac{\mathrm{z}^{m}}{m!} P_{m}=e^{z(\mathrm{x}+b)}\left[1+\frac{2}{n}(a-b) \mathrm{z}+c G(n, n+2(a-b) \mathrm{z})\right]0zmm!Pm=it isz(x+b)[1+2n(Ab)z+cG(n,n+2(Ab)z)]
  1. case k > 1 k > 1 k > 1k>1k>1, that is
P n = x n k ( x + b 1 ) k P n = x n k x + b 1 k P_(n)=x^(n-k)(x+b_(1))^(k)P_{n}=\mathrm{x}^{n-k}\left(\mathrm{x}+b_{1}\right)^{k}Pn=xnk(x+b1)k
n k k , k > 1 , n k k , k > 1 , n-k >= k,quad k > 1,n-k \geq k, \quad k>1,nkk,k>1,
It can be attached to the general case by taking
λ = 1 n 1 λ = 1 n 1 lambda=-(1)/(n-1)\lambda=-\frac{1}{n-1}λ=1n1
as we saw in the previous article.
We found:
λ = 1 n 1 , α = n 2 n 1 , μ = b 1 n 1 , ν = 0 , β = ( k 1 ) b 1 n 1 λ = 1 n 1 , α = n 2 n 1 , μ = b 1 n 1 , ν = 0 , β = ( k 1 ) b 1 n 1 lambda=-(1)/(n-1),alpha=-(n-2)/(n-1),mu=-(b_(1))/(n-1),nu=0,beta=-((k-1)b_(1))/(n-1)\lambda=-\frac{1}{n-1}, \alpha=-\frac{n-2}{n-1}, \mu=-\frac{b_{1}}{n-1}, \nu=0, \beta=-\frac{(k-1) b_{1}}{n-1}λ=1n1,α=n2n1,μ=b1n1,n=0,β=(k1)b1n1
The equation that gives the generating function is written:
we put
z F [ z b 1 + n ] F + k b 1 F = 0 z F z b 1 + n F + k b 1 F = 0 zF^('')-[zb_(1)+n]F^(')+kb_(1)F=0z F^{\prime \prime}-\left[z b_{1}+n\right] F^{\prime}+k b_{1} F=0zF[zb1+n]F+kb1F=0
t F t 2 [ t + n ] F 1 + k F = 0 t F t 2 [ t + n ] F 1 + k F = 0 tF^('')_(t^(2))-[t+n]F^(')_(1)+kF=0t F^{\prime \prime}{ }_{t^{2}}-[t+n] F^{\prime}{ }_{1}+k F=0tFt2[t+n]F1+kF=0
All integrals of this equation are holomorphic about the origin. Int'a= indeed we have a polynomial
i = 0 k k ( k 1 ) k i + 1 ) i ! n ( n 1 ) ( n i + 1 ) t i = P 1 ( t ) i = 0 k k ( k 1 ) k i + 1 i ! n ( n 1 ) ( n i + 1 ) t i = P 1 ( t ) sum_(i=0)^(k)(k(k-1)dots^(k)-i+1))/(i!n(n-1)dots(n-i+1))t^(i)=P_(1)(t)\sum_{i=0}^{k} \frac{\left.k(k-1) \ldots{ }^{k}-i+1\right)}{i!n(n-1) \ldots(n-i+1)} t^{i}=P_{1}(t)and=0kk(k1)kand+1)and!n(n1)(nand+1)tand=P1(t)
which satisfies the equation. Putting
F = e λ φ F = e λ φ F=e^(lambda)varphiF=e^{\lambda} \varphiF=it isλφ
HAVE
t φ ( n t ) φ ( n k ) φ = 0 t φ ( n t ) φ ( n k ) φ = 0 tvarphi^('')-(n-t)varphi^(')-(n-k)varphi=0t \varphi^{\prime \prime}-(n-t) \varphi^{\prime}-(n-k) \varphi=0tφ(nt)φ(nk)φ=0
or changing to t t tttin - t t ttt:
t φ ( n + t ) φ + ( n k ) φ = 0 t φ ( n + t ) φ + ( n k ) φ = 0 tvarphi^('')-(n+t)varphi^(')+(n-k)varphi=0t \varphi^{\prime \prime}-(n+t) \varphi^{\prime}+(n-k) \varphi=0tφ(n+t)φ+(nk)φ=0
So we have the solution distinct from the previous one:
e t i = 0 n k ( 1 ) i ( n k ) ( n k 1 ) ( n k i + 1 ) i ! n ( n 1 ) ( n i + 1 ) i i = e t P 2 ( t ) e t i = 0 n k ( 1 ) i ( n k ) ( n k 1 ) ( n k i + 1 ) i ! n ( n 1 ) ( n i + 1 ) i i = e t P 2 ( t ) e^(t)sum_(i=0)^(n-k)(-1)^(i)((n-k)(n-k-1)dots(n-k-i+1))/(i!n(n-1)dots(n-i+1))i^(i)=e^(t)P_(2)(t)e^{t} \sum_{i=0}^{n-k}(-1)^{i} \frac{(n-k)(n-k-1) \ldots(n-k-i+1)}{i!n(n-1) \ldots(n-i+1)} i^{i}=e^{t} P_{2}(t)it istand=0nk(1)and(nk)(nk1)(nkand+1)and!n(n1)(nand+1)andand=it istP2(t)
So there is
n = 0 z n n ! P n = e ι x [ c P 1 ( b 1 z ) + c 1 e z b 1 P 2 ( b 2 z ) ] n = 0 z n n ! P n = e ι x c P 1 b 1 z + c 1 e z b 1 P 2 b 2 z sum_(n=0)^(oo)(z^(n))/(n!)P_(n)=e^(iota x)[cP_(1)(b_(1)z)+c_(1)e^(z)b_(1)P_(2)(b_(2)z)]\sum_{n=0}^{\infty} \frac{\mathrm{z}^{n}}{n!} P_{n}=e^{\iota x}\left[c P_{1}\left(b_{1} \mathrm{z}\right)+c_{1} e^{z} b_{1} P_{2}\left(b_{2} \mathrm{z}\right)\right]n=0znn!Pn=it isIx[cP1(b1z)+c1it iszb1P2(b2z)]
constants c , c 1 c , c 1 c,c_(1)\boldsymbol{c}, \boldsymbol{c}_{1}c,c1being linked by the relationship
c + c 1 = 1 c + c 1 = 1 c+c_(1)=1c+c_{1}=1c+c1=1
In general we will have the polynomials
n = 0 z n n ! P n = e 2 [ x + b ] [ c P 1 [ ( a b ) z ] + c 1 e [ a b ] z P 2 [ ( a b ) z ) ] n = 0 z n n ! P n = e 2 [ x + b ] c P 1 [ ( a b ) z ] + c 1 e [ a b ] z P 2 [ ( a b ) z ) sum_(n=0)^(oo)(z^(n))/(n!)P_(n)=e^(2[x+b])[cP_(1)[(a-b)z]+c_(1)e^([a-b]z)P_(2)[(a-b)z)]\sum_{n=0}^{\infty} \frac{\mathbf{z}^{n}}{n!} P_{n}=e^{2[x+b]}\left[c P_{1}[(a-b) \mathbf{z}]+c_{1} e^{[a-b] z} P_{2}[(a-b) \mathbf{z})\right]n=0znn!Pn=it is2[x+b][cP1[(Ab)z]+c1it is[Ab]zP2[(Ab)z)]
6. If a B n B n B_(n)B_{n}Bnit is identical we must have
λ = 1 2 n 3 λ = 1 2 n 3 lambda=-(1)/(2n-3)\lambda=-\frac{1}{2 n-3}λ=12n3
and we are in the previous case. This therefore does not present a case distinct from those studied.
Paris, November 8, 1928.
1932

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