a(n) = 9*n^2 + 3*n + 1.

Terms

a(0) =1a(1) =13a(2) =43a(3) =91a(4) =157a(5) =241a(6) =343a(7) =463a(8) =601a(9) =757a(10) =931a(11) =1123a(12) =1333a(13) =1561a(14) =1807a(15) =2071a(16) =2353a(17) =2653a(18) =2971a(19) =3307a(20) =3661a(21) =4033a(22) =4423a(23) =4831a(24) =5257a(25) =5701a(26) =6163a(27) =6643a(28) =7141a(29) =7657