a(n) = Sum_{k=0..n} binomial(3*n+2,k) * binomial(3*n-k-1,n-k).

A386836

a(n) = Sum_{k=0..n} binomial(3*n+2,k) * binomial(3*n-k-1,n-k).

Terms

    a(0) =1a(1) =7a(2) =70a(3) =782a(4) =9199a(5) =111465a(6) =1376764a(7) =17234600a(8) =217891693a(9) =2775766091a(10) =35574777154a(11) =458169648722

External references