a(n) = 64*n^2 - 16.

Terms

a(0) =48a(1) =240a(2) =560a(3) =1008a(4) =1584a(5) =2288a(6) =3120a(7) =4080a(8) =5168a(9) =6384a(10) =7728a(11) =9200a(12) =10800a(13) =12528a(14) =14384a(15) =16368a(16) =18480a(17) =20720a(18) =23088a(19) =25584a(20) =28208a(21) =30960a(22) =33840a(23) =36848a(24) =39984a(25) =43248a(26) =46640a(27) =50160a(28) =53808a(29) =57584