a(n) = 36*n^2 - n.

Terms

a(0) =35a(1) =142a(2) =321a(3) =572a(4) =895a(5) =1290a(6) =1757a(7) =2296a(8) =2907a(9) =3590a(10) =4345a(11) =5172a(12) =6071a(13) =7042a(14) =8085a(15) =9200a(16) =10387a(17) =11646a(18) =12977a(19) =14380a(20) =15855a(21) =17402a(22) =19021a(23) =20712a(24) =22475a(25) =24310a(26) =26217a(27) =28196a(28) =30247a(29) =32370