Nearest integer to (n+1)^3/9.

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =14a(5) =24a(6) =38a(7) =57a(8) =81a(9) =111a(10) =148a(11) =192a(12) =244a(13) =305a(14) =375a(15) =455a(16) =546a(17) =648a(18) =762a(19) =889a(20) =1029a(21) =1183a(22) =1352a(23) =1536a(24) =1736a(25) =1953a(26) =2187a(27) =2439a(28) =2710a(29) =3000