A138477 A084175 interleaved with 2*A084175.

0, 0, 1, 2, 3, 6, 15, 30, 55, 110, 231, 462, 903, 1806, 3655, 7310, 14535, 29070, 58311, 116622, 232903, 465806, 932295, 1864590, 3727815, 7455630, 14913991, 29827982, 59650503, 119301006, 238612935, 477225870, 954429895, 1908859790, 3817763271, 7635526542

Offset: 0

Author

Paul Curtz, May 18 2008

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (2,-1,2,2,-4).

Crossrefs

Cf. A084175.

Programs

Mathematica

LinearRecurrence[{2, -1, 2, 2, -4}, {0, 0, 1, 2, 3}, 40] (* Amiram Eldar, Sep 13 2024 *)

Formula

From R. J. Mathar, May 19 2008: (Start)

O.g.f.: x^2/((2*x-1)(x-1)(1+x)(1+2*x^2)).

a(2n) = A084175(n). a(2n+1) = 2*A084175(n).

a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) + 2*a(n-4) - 4*a(n-5). (End)

Extensions

More terms from R. J. Mathar, May 19 2008