a(n) = n^6 - n^3.

Terms

a(0) =0a(1) =0a(2) =56a(3) =702a(4) =4032a(5) =15500a(6) =46440a(7) =117306a(8) =261632a(9) =530712a(10) =999000a(11) =1770230a(12) =2984256a(13) =4824612a(14) =7526792a(15) =11387250a(16) =16773120a(17) =24132656a(18) =34006392a(19) =47039022a(20) =63992000a(21) =85756860a(22) =113369256a(23) =148023722a(24) =191089152a(25) =244125000a(26) =308898200a(27) =387400806a(28) =481868352a(29) =594798932