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

Terms

a(0) =0a(1) =-2a(2) =2a(3) =18a(4) =52a(5) =110a(6) =198a(7) =322a(8) =488a(9) =702a(10) =970a(11) =1298a(12) =1692a(13) =2158a(14) =2702a(15) =3330a(16) =4048a(17) =4862a(18) =5778a(19) =6802a(20) =7940a(21) =9198a(22) =10582a(23) =12098a(24) =13752a(25) =15550a(26) =17498a(27) =19602a(28) =21868a(29) =24302