a(n) = 14*n^2 + 1.

Terms

a(0) =15a(1) =57a(2) =127a(3) =225a(4) =351a(5) =505a(6) =687a(7) =897a(8) =1135a(9) =1401a(10) =1695a(11) =2017a(12) =2367a(13) =2745a(14) =3151a(15) =3585a(16) =4047a(17) =4537a(18) =5055a(19) =5601a(20) =6175a(21) =6777a(22) =7407a(23) =8065a(24) =8751a(25) =9465a(26) =10207a(27) =10977a(28) =11775a(29) =12601