a(n) = 16n^2 + 32n + 15.

Terms

a(0) =15a(1) =63a(2) =143a(3) =255a(4) =399a(5) =575a(6) =783a(7) =1023a(8) =1295a(9) =1599a(10) =1935a(11) =2303a(12) =2703a(13) =3135a(14) =3599a(15) =4095a(16) =4623a(17) =5183a(18) =5775a(19) =6399a(20) =7055a(21) =7743a(22) =8463a(23) =9215a(24) =9999a(25) =10815a(26) =11663a(27) =12543a(28) =13455a(29) =14399