1+5*n+7*n^2.

Terms

a(0) =13a(1) =39a(2) =79a(3) =133a(4) =201a(5) =283a(6) =379a(7) =489a(8) =613a(9) =751a(10) =903a(11) =1069a(12) =1249a(13) =1443a(14) =1651a(15) =1873a(16) =2109a(17) =2359a(18) =2623a(19) =2901a(20) =3193a(21) =3499a(22) =3819a(23) =4153a(24) =4501a(25) =4863a(26) =5239a(27) =5629a(28) =6033a(29) =6451