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Denominator of Laguerre(n, 1).
2

%I #11 Sep 08 2022 08:45:45

%S 1,1,2,3,8,15,144,420,5760,4536,403200,1995840,6220800,259459200,

%T 1341204480,46702656000,1394852659200,11115232128000,376610217984000,

%U 96543730483200,128047474114560000,1277273554292736000

%N Denominator of Laguerre(n, 1).

%H G. C. Greubel, <a href="/A160622/b160622.txt">Table of n, a(n) for n = 0..450</a>

%F Denominators of coefficients in expansion of exp(-x/(1 - x))/(1 - x). - _Ilya Gutkovskiy_, Aug 29 2018

%e 1, 0, -1/2, -2/3, -5/8, -7/15, -37/144, -17/420, 887/5760, 1405/4536, 168919/403200, 958271/1995840, ... = A160621/A160622.

%t Denominator[Table[LaguerreL[n,1], {n, 0, 50}]] (* _G. C. Greubel_, May 06 2018 *)

%o (PARI) for(n=0,30, print1(denominator(sum(k=0,n, binomial(n,k)*((-1)^k/k!))), ", ")) \\ _G. C. Greubel_, May 06 2018

%o (Magma) [Denominator((&+[Binomial(n,k)*((-1)^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // _G. C. Greubel_, May 06 2018

%Y For numerators see A160621.

%Y Cf. A009940.

%K nonn,frac

%O 0,3

%A _N. J. A. Sloane_, Nov 14 2009