OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..606
FORMULA
a(n) = sum(binomial(3*k,k)^2*(-1)^(n-k)/(2*k+1), k=0..n).
Recurrence: 4*(n+2)^2*(4*n^2+16*n+15) * a(n+2) -(713*n^4+4246*n^3 +9421*n^2 +9224*n+3360) * a(n+1) -9*(9*n^2+27*n+20)^2 * a(n) = 0.
a(n) ~ 3^(6*n+7)/(745*Pi*n^2*2^(4*n+3)). - Vaclav Kotesovec, Aug 06 2013
MATHEMATICA
Table[Sum[Binomial[3k, k]^2(-1)^(n-k)/(2k+1), {k, 0, n}], {n, 0, 20}]
PROG
(Maxima) makelist(sum(binomial(3*k, k)^2*(-1)^(n-k)/(2*k+1), k, 0, n), n, 0, 20);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emanuele Munarini, Apr 08 2011
STATUS
approved