a(n) = 5*n^2 + 5*n - 9.

Terms

a(0) =1a(1) =21a(2) =51a(3) =91a(4) =141a(5) =201a(6) =271a(7) =351a(8) =441a(9) =541a(10) =651a(11) =771a(12) =901a(13) =1041a(14) =1191a(15) =1351a(16) =1521a(17) =1701a(18) =1891a(19) =2091a(20) =2301a(21) =2521a(22) =2751a(23) =2991a(24) =3241a(25) =3501a(26) =3771a(27) =4051a(28) =4341a(29) =4641