a(n) = 26*n^2 + 1.

Terms

a(0) =1a(1) =27a(2) =105a(3) =235a(4) =417a(5) =651a(6) =937a(7) =1275a(8) =1665a(9) =2107a(10) =2601a(11) =3147a(12) =3745a(13) =4395a(14) =5097a(15) =5851a(16) =6657a(17) =7515a(18) =8425a(19) =9387a(20) =10401a(21) =11467a(22) =12585a(23) =13755a(24) =14977a(25) =16251a(26) =17577a(27) =18955a(28) =20385a(29) =21867