a(n) = n^3 - 2*n.

Terms

a(0) =0a(1) =-1a(2) =4a(3) =21a(4) =56a(5) =115a(6) =204a(7) =329a(8) =496a(9) =711a(10) =980a(11) =1309a(12) =1704a(13) =2171a(14) =2716a(15) =3345a(16) =4064a(17) =4879a(18) =5796a(19) =6821a(20) =7960a(21) =9219a(22) =10604a(23) =12121a(24) =13776a(25) =15575a(26) =17524a(27) =19629a(28) =21896a(29) =24331