Mahonian numbers T(n,7) (cf. A008302).

Terms

a(0) =15a(1) =101a(2) =359a(3) =961a(4) =2191a(5) =4489a(6) =8504a(7) =15159a(8) =25728a(9) =41926a(10) =66013a(11) =100913a(12) =150349a(13) =218995a(14) =312646a(15) =438407a(16) =604902a(17) =822504a(18) =1103587a(19) =1462801a(20) =1917371a(21) =2487421a(22) =3196324a(23) =4071079a(24) =5142716a(25) =6446730a(26) =8023545a(27) =9919009a(28) =12184921a(29) =14879591