a(n) = 81*n^2 - 2*n.

Terms

a(0) =79a(1) =320a(2) =723a(3) =1288a(4) =2015a(5) =2904a(6) =3955a(7) =5168a(8) =6543a(9) =8080a(10) =9779a(11) =11640a(12) =13663a(13) =15848a(14) =18195a(15) =20704a(16) =23375a(17) =26208a(18) =29203a(19) =32360a(20) =35679a(21) =39160a(22) =42803a(23) =46608a(24) =50575a(25) =54704a(26) =58995a(27) =63448a(28) =68063a(29) =72840