a(n) = n*(3*n + 4).

Terms

a(0) =0a(1) =7a(2) =20a(3) =39a(4) =64a(5) =95a(6) =132a(7) =175a(8) =224a(9) =279a(10) =340a(11) =407a(12) =480a(13) =559a(14) =644a(15) =735a(16) =832a(17) =935a(18) =1044a(19) =1159a(20) =1280a(21) =1407a(22) =1540a(23) =1679a(24) =1824a(25) =1975a(26) =2132a(27) =2295a(28) =2464a(29) =2639