a(n) = Sum_{k=0..n-1} binomial(5*k,k) * binomial(5*n-5*k,n-k-1).

A386613

a(n) = Sum_{k=0..n-1} binomial(5*k,k) * binomial(5*n-5*k,n-k-1).

Terms

    a(0) =0a(1) =1a(2) =15a(3) =200a(4) =2570a(5) =32470a(6) =406411a(7) =5057440a(8) =62692100a(9) =775007135a(10) =9561421830a(11) =117780193480

External references