Triangle of numbers n!(n-1)!...(n-k+1)!/(1!2!...k!).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =1a(7) =6a(8) =6a(9) =1a(10) =1a(11) =24a(12) =72a(13) =24a(14) =1a(15) =1a(16) =120a(17) =1440a(18) =1440a(19) =120a(20) =1a(21) =1a(22) =720a(23) =43200a(24) =172800a(25) =43200a(26) =720a(27) =1a(28) =1a(29) =5040