a(n) = 225*n^2 + 15.

Terms

a(0) =15a(1) =240a(2) =915a(3) =2040a(4) =3615a(5) =5640a(6) =8115a(7) =11040a(8) =14415a(9) =18240a(10) =22515a(11) =27240a(12) =32415a(13) =38040a(14) =44115a(15) =50640a(16) =57615a(17) =65040a(18) =72915a(19) =81240a(20) =90015a(21) =99240a(22) =108915a(23) =119040a(24) =129615a(25) =140640a(26) =152115a(27) =164040a(28) =176415a(29) =189240