OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
László Németh, Tetrahedron trinomial coefficient transform, arXiv:1905.13475 [math.CO], 2019.
FORMULA
Recurrence: (n+3)*(3*n+1)*a(n) = 3*(6*n^2+15*n+11)*a(n-1) - 5*(n-1)*(3*n+4)*a(n-2). - Vaclav Kotesovec, Oct 08 2012
a(n) ~ 4*5^(n+1/2)/sqrt(Pi*n). - Vaclav Kotesovec, Oct 08 2012
MATHEMATICA
Table[Sum[Binomial[n, k]*Binomial[2*k+3, k], {k, 0, n}], {n, 0, 25}] (* Vaclav Kotesovec, Oct 08 2012 *)
PROG
(PARI) a(n)=sum(k=0, n, binomial(n, k)*binomial(2*k+3, k)); \\ Joerg Arndt, May 04 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved