a(n) = (1/(4n+2))*M(3n; n,n,n).

A024487

a(n) = (1/(4n+2))*M(3n; n,n,n).

Terms

    a(0) =1a(1) =9a(2) =120a(3) =1925a(4) =34398a(5) =659736a(6) =13302432a(7) =278397405a(8) =5996669250a(9) =132166590270

External references