a(n) = 841*n^2 - 2*n.

Terms

a(0) =839a(1) =3360a(2) =7563a(3) =13448a(4) =21015a(5) =30264a(6) =41195a(7) =53808a(8) =68103a(9) =84080a(10) =101739a(11) =121080a(12) =142103a(13) =164808a(14) =189195a(15) =215264a(16) =243015a(17) =272448a(18) =303563a(19) =336360a(20) =370839a(21) =407000a(22) =444843a(23) =484368a(24) =525575a(25) =568464a(26) =613035a(27) =659288a(28) =707223a(29) =756840