Number of 4-block ordered tricoverings of an unlabeled n-set.

Terms

a(0) =4a(1) =13a(2) =28a(3) =50a(4) =80a(5) =119a(6) =168a(7) =228a(8) =300a(9) =385a(10) =484a(11) =598a(12) =728a(13) =875a(14) =1040a(15) =1224a(16) =1428a(17) =1653a(18) =1900a(19) =2170a(20) =2464a(21) =2783a(22) =3128a(23) =3500a(24) =3900a(25) =4329a(26) =4788a(27) =5278a(28) =5800a(29) =6355