a(n) = (2*n + 1)*(5*n + 1).

Terms

a(0) =1a(1) =18a(2) =55a(3) =112a(4) =189a(5) =286a(6) =403a(7) =540a(8) =697a(9) =874a(10) =1071a(11) =1288a(12) =1525a(13) =1782a(14) =2059a(15) =2356a(16) =2673a(17) =3010a(18) =3367a(19) =3744a(20) =4141a(21) =4558a(22) =4995a(23) =5452a(24) =5929a(25) =6426a(26) =6943a(27) =7480a(28) =8037a(29) =8614