A090409 7*8^n/9+2(-1)^n/9.

1, 6, 50, 398, 3186, 25486, 203890, 1631118, 13048946, 104391566, 835132530, 6681060238, 53448481906, 427587855246, 3420702841970, 27365622735758, 218924981886066, 1751399855088526, 14011198840708210, 112089590725665678

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (7,8).

Formula

a(n)=sum{j=0..2, sum{k=0..n, C(3n+j, 3k) }}/3; a(n)=(A007613(n)+A082311(n)+A082365(n))/3.

G.f.: ( -1+x ) / ( (1+x)*(8*x-1) ). - R. J. Mathar, Dec 10 2014

Mathematica

LinearRecurrence[{7, 8}, {1, 6}, 20] (* Harvey P. Dale, Aug 15 2016 *)

Crossrefs

First differences of A015565.

Sequence in context: A308860 A318162 A027330 * A212233 A180910 A199680

Adjacent sequences: A090406 A090407 A090408 * A090410 A090411 A090412

Keyword

easy,nonn

Author

Paul Barry, Nov 29 2003

Status

approved