a(n) = 3*n^3 + n^2 - 4*n.

Terms

a(0) =0a(1) =0a(2) =20a(3) =78a(4) =192a(5) =380a(6) =660a(7) =1050a(8) =1568a(9) =2232a(10) =3060a(11) =4070a(12) =5280a(13) =6708a(14) =8372a(15) =10290a(16) =12480a(17) =14960a(18) =17748a(19) =20862a(20) =24320a(21) =28140a(22) =32340a(23) =36938a(24) =41952a(25) =47400a(26) =53300a(27) =59670a(28) =66528a(29) =73892