A095795 a(0)=2, a(1)=5, a(n+2) = a(n+1) + (-1)^n a(n).

2, 5, 7, 2, 9, 7, 16, 9, 25, 16, 41, 25, 66, 41, 107, 66, 173, 107, 280, 173, 453, 280, 733, 453, 1186, 733, 1919, 1186, 3105, 1919, 5024, 3105, 8129, 5024, 13153, 8129, 21282, 13153, 34435, 21282, 55717, 34435, 90152, 55717, 145869, 90152, 236021, 145869

Offset: 0

Author

Gary W. Adamson, Jun 06 2004

Keywords

• nonn
• easy

Comments

Alternate terms form a Lucas sequence.

Specifically, a(2n) = A022113(n). - Jonathan Vos Post, Nov 16 2005

Links

• Eric Weisstein's World of Mathematics, Lucas Sequence.
• Index entries for linear recurrences with constant coefficients, signature (0,1,0,1).

Crossrefs

Cf. A022113.

Programs

Mathematica

CoefficientList[Series[(3*x^3 - 5*x^2 - 5*x - 2)/(x^4 + x^2 - 1), {x, 0, 50}], x] (* Wesley Ivan Hurt, Jan 21 2017 *)

Formula

a(n) = a(n-2) + a(n-4). G.f.: (3*x^3-5*x^2-5*x-2) / (x^4+x^2-1). - Colin Barker, Oct 18 2013

Extensions

Edited by Don Reble, Nov 15 2005

Missing terms inserted and more terms added by Colin Barker, Oct 18 2013