a(n) = 32*n^2 - 1.

Terms

a(0) =31a(1) =127a(2) =287a(3) =511a(4) =799a(5) =1151a(6) =1567a(7) =2047a(8) =2591a(9) =3199a(10) =3871a(11) =4607a(12) =5407a(13) =6271a(14) =7199a(15) =8191a(16) =9247a(17) =10367a(18) =11551a(19) =12799a(20) =14111a(21) =15487a(22) =16927a(23) =18431a(24) =19999a(25) =21631a(26) =23327a(27) =25087a(28) =26911a(29) =28799