a(n) = -1 + n + 4*n^2.

Terms

a(0) =-1a(1) =4a(2) =17a(3) =38a(4) =67a(5) =104a(6) =149a(7) =202a(8) =263a(9) =332a(10) =409a(11) =494a(12) =587a(13) =688a(14) =797a(15) =914a(16) =1039a(17) =1172a(18) =1313a(19) =1462a(20) =1619a(21) =1784a(22) =1957a(23) =2138a(24) =2327a(25) =2524a(26) =2729a(27) =2942a(28) =3163a(29) =3392