OFFSET
0,4
COMMENTS
The recurrence is same as for A119363. - Vaclav Kotesovec, Mar 12 2019
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
a(n) ~ 4^n / (3*sqrt(Pi*n)). - Vaclav Kotesovec, Mar 12 2019
MATHEMATICA
Table[Sum[Binomial[n, 3*k + 2]^2, {k, 0, n}], {n, 0, 40}] (* Vaclav Kotesovec, Mar 12 2019 *)
PROG
(PARI) a(n) = sum(k=0, n, binomial(n, 3*k+2)^2); \\ Michel Marcus, Mar 12 2019
(Magma) [&+[Binomial(n, 3*k+2)^2: k in [0..n]]: n in [0..30]]; // Vincenzo Librandi, Mar 14 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 12 2008
STATUS
approved