a(n) = 18*n^2 - 1.

Terms

a(0) =17a(1) =71a(2) =161a(3) =287a(4) =449a(5) =647a(6) =881a(7) =1151a(8) =1457a(9) =1799a(10) =2177a(11) =2591a(12) =3041a(13) =3527a(14) =4049a(15) =4607a(16) =5201a(17) =5831a(18) =6497a(19) =7199a(20) =7937a(21) =8711a(22) =9521a(23) =10367a(24) =11249a(25) =12167a(26) =13121a(27) =14111a(28) =15137a(29) =16199