Triangle t(n,m) = (n*m)!/(m!^n) read by rows, 0<=m<=n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =6a(6) =1a(7) =6a(8) =90a(9) =1680a(10) =1a(11) =24a(12) =2520a(13) =369600a(14) =63063000a(15) =1a(16) =120a(17) =113400a(18) =168168000a(19) =305540235000a(21) =1a(22) =720a(23) =7484400a(24) =137225088000