a(n) = 4*n^2 - 6*n + 3.

Terms

a(0) =1a(1) =7a(2) =21a(3) =43a(4) =73a(5) =111a(6) =157a(7) =211a(8) =273a(9) =343a(10) =421a(11) =507a(12) =601a(13) =703a(14) =813a(15) =931a(16) =1057a(17) =1191a(18) =1333a(19) =1483a(20) =1641a(21) =1807a(22) =1981a(23) =2163a(24) =2353a(25) =2551a(26) =2757a(27) =2971a(28) =3193a(29) =3423