a(n) = 2*n^3 + 1.

Terms

a(0) =1a(1) =3a(2) =17a(3) =55a(4) =129a(5) =251a(6) =433a(7) =687a(8) =1025a(9) =1459a(10) =2001a(11) =2663a(12) =3457a(13) =4395a(14) =5489a(15) =6751a(16) =8193a(17) =9827a(18) =11665a(19) =13719a(20) =16001a(21) =18523a(22) =21297a(23) =24335a(24) =27649a(25) =31251a(26) =35153a(27) =39367a(28) =43905a(29) =48779