A021854 Expansion of 1/((1-x)(1-4x)(1-7x)(1-8x)).

1, 20, 265, 2940, 29601, 280740, 2558905, 22683980, 197048401, 1685772660, 14253277545, 119401486620, 992861126401, 8206523123780, 67497981692185, 552905862106860, 4513706683463601, 36742894880462100

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (20,-135,340,-224).

Formula

a(n) = (9*8^(n+3) - 14*7^(n+3) + 7*4^(n+3) - 2)/252. - Yahia Kahloune, Jul 05 2013

Mathematica

CoefficientList[Series[1 / ((1 - x) (1 - 4 x) (1 - 7 x)  (1 - 8 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 11 2013 *)
LinearRecurrence[{20, -135, 340, -224}, {1, 20, 265, 2940}, 30] (* Harvey P. Dale, Dec 26 2022 *)

Crossrefs

Sequence in context: A208948 A278408 A229562 * A025939 A278773 A021824

Adjacent sequences: A021851 A021852 A021853 * A021855 A021856 A021857

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved