a(n) = 9*n^2 - 3*n + 1 with n>0.

Terms

a(0) =7a(1) =31a(2) =73a(3) =133a(4) =211a(5) =307a(6) =421a(7) =553a(8) =703a(9) =871a(10) =1057a(11) =1261a(12) =1483a(13) =1723a(14) =1981a(15) =2257a(16) =2551a(17) =2863a(18) =3193a(19) =3541a(20) =3907a(21) =4291a(22) =4693a(23) =5113a(24) =5551a(25) =6007a(26) =6481a(27) =6973a(28) =7483a(29) =8011