a(n) = 2*n^3 + 9*n^2 + 9*n.

Terms

a(0) =0a(1) =20a(2) =70a(3) =162a(4) =308a(5) =520a(6) =810a(7) =1190a(8) =1672a(9) =2268a(10) =2990a(11) =3850a(12) =4860a(13) =6032a(14) =7378a(15) =8910a(16) =10640a(17) =12580a(18) =14742a(19) =17138a(20) =19780a(21) =22680a(22) =25850a(23) =29302a(24) =33048a(25) =37100a(26) =41470a(27) =46170a(28) =51212a(29) =56608