a(n) = binomial(10*n+2,n)/(5*n+1).

A234525

a(n) = binomial(10*n+2,n)/(5*n+1).

Terms

    a(0) =1a(1) =2a(2) =21a(3) =310a(4) =5330a(5) =99960a(6) =1983049a(7) =40919714a(8) =869304150a(9) =18885977110a(10) =417663940540

External references