a(n) = 66*n^2 - 1.

Terms

a(0) =65a(1) =263a(2) =593a(3) =1055a(4) =1649a(5) =2375a(6) =3233a(7) =4223a(8) =5345a(9) =6599a(10) =7985a(11) =9503a(12) =11153a(13) =12935a(14) =14849a(15) =16895a(16) =19073a(17) =21383a(18) =23825a(19) =26399a(20) =29105a(21) =31943a(22) =34913a(23) =38015a(24) =41249a(25) =44615a(26) =48113a(27) =51743a(28) =55505a(29) =59399