a(n) = 3*n*(4*n-1).

Terms

a(0) =0a(1) =9a(2) =42a(3) =99a(4) =180a(5) =285a(6) =414a(7) =567a(8) =744a(9) =945a(10) =1170a(11) =1419a(12) =1692a(13) =1989a(14) =2310a(15) =2655a(16) =3024a(17) =3417a(18) =3834a(19) =4275a(20) =4740a(21) =5229a(22) =5742a(23) =6279a(24) =6840a(25) =7425a(26) =8034a(27) =8667a(28) =9324a(29) =10005