a(n) = 3*n^2 + 6*n.

Terms

a(0) =0a(1) =9a(2) =24a(3) =45a(4) =72a(5) =105a(6) =144a(7) =189a(8) =240a(9) =297a(10) =360a(11) =429a(12) =504a(13) =585a(14) =672a(15) =765a(16) =864a(17) =969a(18) =1080a(19) =1197a(20) =1320a(21) =1449a(22) =1584a(23) =1725a(24) =1872a(25) =2025a(26) =2184a(27) =2349a(28) =2520a(29) =2697