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

Terms

a(0) =9a(1) =21a(2) =57a(3) =129a(4) =249a(5) =429a(6) =681a(7) =1017a(8) =1449a(9) =1989a(10) =2649a(11) =3441a(12) =4377a(13) =5469a(14) =6729a(15) =8169a(16) =9801a(17) =11637a(18) =13689a(19) =15969a(20) =18489a(21) =21261a(22) =24297a(23) =27609a(24) =31209a(25) =35109a(26) =39321a(27) =43857a(28) =48729a(29) =53949