a(n) = 78*n^2 - 1.

Terms

a(0) =77a(1) =311a(2) =701a(3) =1247a(4) =1949a(5) =2807a(6) =3821a(7) =4991a(8) =6317a(9) =7799a(10) =9437a(11) =11231a(12) =13181a(13) =15287a(14) =17549a(15) =19967a(16) =22541a(17) =25271a(18) =28157a(19) =31199a(20) =34397a(21) =37751a(22) =41261a(23) =44927a(24) =48749a(25) =52727a(26) =56861a(27) =61151a(28) =65597a(29) =70199