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

A378326

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

Terms

    a(0) =1a(1) =1a(2) =3a(3) =19a(4) =219a(5) =3901a(6) =95838a(7) =3022909a(8) =116798643a(9) =5350403737a(10) =283728025998

External references