a(n) = 900*n^2 - 30.

Terms

a(0) =870a(1) =3570a(2) =8070a(3) =14370a(4) =22470a(5) =32370a(6) =44070a(7) =57570a(8) =72870a(9) =89970a(10) =108870a(11) =129570a(12) =152070a(13) =176370a(14) =202470a(15) =230370a(16) =260070a(17) =291570a(18) =324870a(19) =359970a(20) =396870a(21) =435570a(22) =476070a(23) =518370a(24) =562470a(25) =608370a(26) =656070a(27) =705570a(28) =756870a(29) =809970