A129973 a(n) = A000045(n) - A000931(n).

0, 0, 0, 1, 1, 3, 5, 9, 16, 27, 46, 77, 128, 212, 349, 573, 938, 1532, 2498, 4067, 6614, 10746, 17446, 28306, 45903, 74409, 120577, 195337, 316379, 512332, 829527, 1342940, 2173899, 3518736, 5695148, 9217213, 14916771, 24139826, 39064336

Offset: 1

Author

Roger L. Bagula, Jun 13 2007

Keywords

• nonn
• easy
• less

Links

• Index entries for linear recurrences with constant coefficients, signature (1,2,0,-2,-1).

Crossrefs

Cf. A000045, A000931.

Programs

Mathematica

LinearRecurrence[{1,2,0,-2,-1},{0,0,0,1,1},40] (* Harvey P. Dale, Jan 31 2024 *)

PARI

a(n)=([0,1,0,0,0; 0,0,1,0,0; 0,0,0,1,0; 0,0,0,0,1; -1,-2,0,2,1]^(n-1)*[0;0;0;1;1])[1,1] \\ Charles R Greathouse IV, Oct 03 2016

Formula

G.f.: x^4/((1-x-x^2)(1-x^2-x^3)). a(n)=a(n-1)+2*a(n-2)-2*a(n-4)-a(n-5). - R. J. Mathar, Oct 30 2008