A160616 Denominator of Laguerre(n, -2).

1, 1, 1, 3, 1, 15, 45, 105, 315, 405, 4725, 155925, 467775, 96525, 42567525, 638512875, 30405375, 10854718875, 97692469875, 618718975875, 189403768125, 194896477400625, 238206805711875, 7044115540336875, 8701554491004375

Offset: 0

Author

N. J. A. Sloane, Nov 14 2009

Keywords

• nonn
• frac

Examples

			1, 3, 7, 43/3, 27, 719/15, 3661/45, 13991/105, 66769/315, 133261/405, 2363513/4725, 116441047/155925, ...
		

Links

• Matthew House, Table of n, a(n) for n = 0..506
• Eric Weisstein's World of Mathematics, Laguerre Polynomial.

Crossrefs

For numerators see A160615.

Cf. A087912.

Programs

Magma

[Denominator((&+[Binomial(n,k)*(2^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 06 2018

Mathematica

Denominator[Table[LaguerreL[n, -2], {n, 0, 50}]] (* G. C. Greubel, May 06 2018 *)

PARI

a(n) = sum(k=0, n, (-1)^k*binomial(n, k)*(-2)^k/k!); \\ Michel Marcus, Aug 10 2015

Formula

Denominators of coefficients in expansion of exp(2*x/(1 - x))/(1 - x). - Ilya Gutkovskiy, Aug 29 2018