A279335 Denominators of coefficients in expansion of exp(x)/(1 - x - x^2).

1, 1, 2, 3, 24, 60, 720, 2520, 40320, 25920, 3628800, 19958400, 479001600, 3113510400, 87178291200, 653837184000, 2988969984000, 1243662336000, 6402373705728000, 5529322745856000, 143111882833920000, 115590366904320000, 1124000727777607680000

Offset

0,3

Comments

a(n) is the denominator of Sum_{k=0..n} A000045(n-k)/k!. - Robert Israel, Dec 26 2016

Links

Clark Kimberling, Table of n, a(n) for n = 0..1000

Example

(1/1) + (2/1)x + (7/2)x^2 + (17/3)x^3 + (221/24)x^4 ... ; 1/1, 2/1, 7/2, 17/3, ... = A279334/A279335.

Maple

S:= series(exp(x)/(1-x-x^2), x, 101):
seq(denom(coeff(S, x, j)), j=0..100); # Robert Israel, Dec 26 2016

Mathematica

z = 30; t = CoefficientList[Series[E^x/(1 - x - x^2), {x, 0, z}], x];
Numerator[t]  (* A279334 *)
Denominator[t]  (* A279335 *)

Crossrefs

Cf. A000045, A279334.

Sequence in context: A118204 A061355 A160618 * A343566 A057665 A371480

Adjacent sequences: A279332 A279333 A279334 * A279336 A279337 A279338

Keyword

nonn,easy,frac

Author

Clark Kimberling, Dec 12 2016

Status

approved