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

Terms

a(0) =0a(1) =0a(2) =1a(3) =3a(4) =6a(5) =10a(6) =16a(7) =24a(8) =35a(9) =49a(10) =66a(11) =86a(12) =110a(13) =138a(14) =171a(15) =209a(16) =252a(17) =300a(18) =354a(19) =414a(20) =481a(21) =555a(22) =636a(23) =724a(24) =820a(25) =924a(26) =1037a(27) =1159a(28) =1290a(29) =1430