a(n) = 8*n + 1.

Terms

a(0) =1a(1) =9a(2) =17a(3) =25a(4) =33a(5) =41a(6) =49a(7) =57a(8) =65a(9) =73a(10) =81a(11) =89a(12) =97a(13) =105a(14) =113a(15) =121a(16) =129a(17) =137a(18) =145a(19) =153a(20) =161a(21) =169a(22) =177a(23) =185a(24) =193a(25) =201a(26) =209a(27) =217a(28) =225a(29) =233