OFFSET
0,3
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, 3k+1]^2, {k, 0, n}], {n, 0, 30}] (* Harvey P. Dale, Sep 08 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 12 2008
STATUS
approved