a(n) = 25*n^2 - 36*n + 13.

Terms

a(0) =13a(1) =2a(2) =41a(3) =130a(4) =269a(5) =458a(6) =697a(7) =986a(8) =1325a(9) =1714a(10) =2153a(11) =2642a(12) =3181a(13) =3770a(14) =4409a(15) =5098a(16) =5837a(17) =6626a(18) =7465a(19) =8354a(20) =9293a(21) =10282a(22) =11321a(23) =12410a(24) =13549a(25) =14738a(26) =15977a(27) =17266a(28) =18605a(29) =19994