a(n) = 625*n^2 - 25.

Terms

a(0) =600a(1) =2475a(2) =5600a(3) =9975a(4) =15600a(5) =22475a(6) =30600a(7) =39975a(8) =50600a(9) =62475a(10) =75600a(11) =89975a(12) =105600a(13) =122475a(14) =140600a(15) =159975a(16) =180600a(17) =202475a(18) =225600a(19) =249975a(20) =275600a(21) =302475a(22) =330600a(23) =359975a(24) =390600a(25) =422475a(26) =455600a(27) =489975a(28) =525600a(29) =562475