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

A291699

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

Terms

    a(0) =1a(1) =1a(2) =8a(3) =135a(4) =3584a(5) =131250a(6) =6158592a(7) =353299947a(8) =23991418880

External references