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

A383716

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

Terms

    a(0) =1a(1) =9a(2) =127a(3) =2001a(4) =33151a(5) =565249a(6) =9819391a(7) =172826369a(8) =3071424511a(9) =54992986113a(10) =990477877247

External references