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

0,4

Links

Matthew House, Table of n, a(n) for n = 0..506

Eric Weisstein's World of Mathematics, Laguerre Polynomial.

Formula

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

Example

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

Mathematica

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

Prog

(PARI) a(n) = sum(k=0, n, (-1)^k*binomial(n, k)*(-2)^k/k!); \\ Michel Marcus, Aug 10 2015
(Magma) [Denominator((&+[Binomial(n, k)*(2^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 06 2018

Crossrefs

For numerators see A160615.

Cf. A087912.

Sequence in context: A053485 A160628 A160604 * A362847 A168319 A326374

Adjacent sequences: A160613 A160614 A160615 * A160617 A160618 A160619

Keyword

nonn,frac

Author

N. J. A. Sloane, Nov 14 2009

Status

approved