a(n) = (1/4) * Sum_{k=0..n-1} binomial(6*n,6*k+3).

A387747

a(n) = (1/4) * Sum_{k=0..n-1} binomial(6*n,6*k+3).

Terms

    a(0) =0a(1) =5a(2) =110a(3) =12563a(4) =654764a(5) =45934985a(6) =2831026490a(7) =184123634063

External references