A025987 Expansion of 1/((1-2*x)*(1-5*x)*(1-6*x)*(1-8*x)).

1, 21, 285, 3185, 31941, 299481, 2685565, 23352945, 198684981, 1663903241, 13774041645, 113050606305, 921961387621, 7483064823801, 60518933442525, 488128819261265, 3929148977523861, 31579173926461161, 253515641877912205, 2033450426964165825, 16299714113077237701

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..900

Index entries for linear recurrences with constant coefficients, signature (21,-156,476,-480).

Formula

a(n) = (2*8^(n+3)-9*6^(n+3)+8*5^(n+3)-2^(n+3))/72. - Yahia Kahloune, May 25 2013

a(n) = (5^(n+1)-2^(n+1))/3+14*a(n-1)-48*a(n-2). - Vincenzo Librandi, Jul 05 2026

Mathematica

a[0]=1; a[1]=21; Do[a[n]=(5^(n+1)-2^(n+1))/3+14*a[n-1]-48*a[n-2], {n, 2, 22}]; Table[a[n], {n, 0, 20}] (* Vincenzo Librandi, Jul 05 2026 *)

Prog

(Magma) I:=[1, 21]; [n le 2 select I[n] else (5^n-2^n)/3+14*Self(n-1)-48*Self(n-2): n in [1..21]]; // Vincenzo Librandi, Jul 05 2026

Crossrefs

Sequence in context: A323063 A028033 A176711 * A125456 A296333 A028028

Adjacent sequences: A025984 A025985 A025986 * A025988 A025989 A025990

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Vincenzo Librandi, Jul 05 2026

Status

approved