Partial sums of ceiling(n^2/6).

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =7a(5) =12a(6) =18a(7) =27a(8) =38a(9) =52a(10) =69a(11) =90a(12) =114a(13) =143a(14) =176a(15) =214a(16) =257a(17) =306a(18) =360a(19) =421a(20) =488a(21) =562a(22) =643a(23) =732a(24) =828a(25) =933a(26) =1046a(27) =1168a(28) =1299a(29) =1440