A025943 Expansion of 1/((1-2*x)*(1-3*x)*(1-7*x)*(1-8*x)).

1, 20, 263, 2890, 28833, 271320, 2457211, 21670550, 187473605, 1598611300, 13480822719, 112690635330, 935435043817, 7720854845360, 63428474542787, 519059289782830, 4233894901355469, 34441103679651900, 279518441880609415, 2264074825634370650, 18308089649659688561, 147833154540747437320

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (20,-137,370,-336).

Formula

a(n) = -2^(n+2)/15+4*8^(n+2)/15+3^(n+3)/20-7^(n+3)/20. - R. J. Mathar, Jun 04 2013

a(n) = 3^(n+1)-2^(n+1)+15*a(n-1)-56*a(n-2). - Vincenzo Librandi, May 07 2026

Mathematica

a[0]=1; a[1]=20; a[n_]:=a[n]=3^(n+1)-2^(n+1)+15*a[n-1]-56*a[n-2]; Table[a[n], {n, 0, 25}] (* Vincenzo Librandi, May 07 2026 *)

Prog

(Magma) I:=[1, 20]; [n le 2 select I[n] else 3^n-2^n+15*Self(n-1)-56*Self(n-2):n in [1..25]]; // Vincenzo Librandi, May 07 2026

Crossrefs

Sequence in context: A041764 A395785 A022111 * A025961 A208948 A278408

Adjacent sequences: A025940 A025941 A025942 * A025944 A025945 A025946

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Vincenzo Librandi, May 07 2026

Status

approved