Triangle T(n,k) of k-block ordered tricoverings of an unlabeled n-set (n >= 3, k = 4..2n).

Terms

a(0) =4a(1) =60a(2) =120a(3) =13a(4) =375a(5) =3030a(6) =9030a(7) =5040a(8) =28a(9) =1392a(10) =24552a(11) =207900a(12) =838320a(13) =1345680a(14) =362880a(15) =50a(16) =4020a(17) =130740a(18) =2208430a(19) =20334720a(20) =101752560a(21) =257065200a(22) =261122400a(23) =46569600a(24) =80a(25) =9960a(26) =551640a(27) =16365410a(28) =274814760a(29) =2709457128