Mahonian numbers T(n,6) (cf. A008302).

Terms

a(0) =1a(1) =20a(2) =90a(3) =259a(4) =602a(5) =1230a(6) =2298a(7) =4015a(8) =6655a(9) =10569a(10) =16198a(11) =24087a(12) =34900a(13) =49436a(14) =68646a(15) =93651a(16) =125761a(17) =166495a(18) =217602a(19) =281083a(20) =359214a(21) =454570a(22) =570050a(23) =708903a(24) =874755a(25) =1071637a(26) =1304014a(27) =1576815a(28) =1895464a(29) =2265912