a(n) = 784*n^2 - 28.

Terms

a(0) =756a(1) =3108a(2) =7028a(3) =12516a(4) =19572a(5) =28196a(6) =38388a(7) =50148a(8) =63476a(9) =78372a(10) =94836a(11) =112868a(12) =132468a(13) =153636a(14) =176372a(15) =200676a(16) =226548a(17) =253988a(18) =282996a(19) =313572a(20) =345716a(21) =379428a(22) =414708a(23) =451556a(24) =489972a(25) =529956a(26) =571508a(27) =614628a(28) =659316a(29) =705572