A373906 a(n) = Sum_{k=0..floor(n/4)} binomial(n+2*k,n-4*k).
1, 1, 1, 1, 2, 8, 29, 85, 212, 476, 1016, 2172, 4825, 11213, 26763, 64095, 151851, 354737, 820328, 1889968, 4361521, 10106859, 23509678, 54793282, 127709888, 297336790, 691382201, 1606284377, 3731020629, 8668253125, 20146856893, 46840732201, 108918637566, 253262275888
Offset: 0
Links
- Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-14,6,-1).
Programs
-
PARI
a(n) = sum(k=0, n\4, binomial(n+2*k, n-4*k));
Formula
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 14*a(n-4) + 6*a(n-5) - a(n-6).
G.f.: 1/(1 - x - x^4/(1 - x)^5).