a(n) = binomial(2*binomial(2*n,n-1),binomial(2*n,n-1)-1).

A101355

a(n) = binomial(2*binomial(2*n,n-1),binomial(2*n,n-1)-1).

Terms

    a(0) =1a(1) =56a(2) =145422675

External references