A097336 Sum k=0..n, C(n-k, floor(k/2))4^k.

1, 5, 5, 21, 101, 181, 517, 2133, 5029, 13301, 47429, 127893, 340709, 1099573, 3145861, 8597205, 26190373, 76524149, 214079429, 633125397, 1857511781, 5282782645, 15412788997, 45132977493, 129657499813, 376262123765

Offset: 0

Author

Paul Barry, Aug 05 2004

Keywords

• easy
• nonn

Comments

The sequence sum{k=0..n, C(n-k,floor(k/2))r^k} has g.f. (1+rx)/(1-x-r^2x^3).

Links

• Index entries for linear recurrences with constant coefficients, signature (1,0,16)

Crossrefs

Cf. A097333, A097334, A097335.

Programs

Mathematica

LinearRecurrence[{1,0,16},{1,5,5},30] (* Harvey P. Dale, Sep 15 2011 *)

Formula

G.f. : (1+4x)/(1-x-16x^3); a(n)=a(n-1)+16a(n-3).