Triangle read by rows: Sum_{j=0..k} binomial(n, j)*binomial(k, j)*j!.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =3a(5) =7a(6) =1a(7) =4a(8) =13a(9) =34a(10) =1a(11) =5a(12) =21a(13) =73a(14) =209a(15) =1a(16) =6a(17) =31a(18) =136a(19) =501a(20) =1546a(21) =1a(22) =7a(23) =43a(24) =229a(25) =1045a(26) =4051a(27) =13327a(28) =1a(29) =8