a(n) = 4^n*(3*n)!/((n+1)!*(2*n+1)!).

A006335

a(n) = 4^n*(3*n)!/((n+1)!*(2*n+1)!).

Terms

    a(0) =1a(1) =2a(2) =16a(3) =192a(4) =2816a(5) =46592a(6) =835584a(7) =15876096a(8) =315031552a(9) =6466437120a(10) =136383037440

External references