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

Terms

a(0) =80a(1) =322a(2) =726a(3) =1292a(4) =2020a(5) =2910a(6) =3962a(7) =5176a(8) =6552a(9) =8090a(10) =9790a(11) =11652a(12) =13676a(13) =15862a(14) =18210a(15) =20720a(16) =23392a(17) =26226a(18) =29222a(19) =32380a(20) =35700a(21) =39182a(22) =42826a(23) =46632a(24) =50600a(25) =54730a(26) =59022a(27) =63476a(28) =68092a(29) =72870