Triangle read by rows: T(n, k) = (n*k)!/(n!)^k.

Terms

a(0) =1a(1) =1a(2) =6a(3) =1a(4) =20a(5) =1680a(6) =1a(7) =70a(8) =34650a(9) =63063000a(10) =1a(11) =252a(12) =756756a(13) =11732745024a(15) =1a(16) =924a(17) =17153136a(21) =1a(22) =3432a(23) =399072960