a(n) = n^3 - floor( n/3 ).

Terms

a(0) =0a(1) =1a(2) =8a(3) =26a(4) =63a(5) =124a(6) =214a(7) =341a(8) =510a(9) =726a(10) =997a(11) =1328a(12) =1724a(13) =2193a(14) =2740a(15) =3370a(16) =4091a(17) =4908a(18) =5826a(19) =6853a(20) =7994a(21) =9254a(22) =10641a(23) =12160a(24) =13816a(25) =15617a(26) =17568a(27) =19674a(28) =21943a(29) =24380