a(n) = Sum_{k=1..n} (k^2*floor(k/2)).

Terms

a(0) =0a(1) =4a(2) =13a(3) =45a(4) =95a(5) =203a(6) =350a(7) =606a(8) =930a(9) =1430a(10) =2035a(11) =2899a(12) =3913a(13) =5285a(14) =6860a(15) =8908a(16) =11220a(17) =14136a(18) =17385a(19) =21385a(20) =25795a(21) =31119a(22) =36938a(23) =43850a(24) =51350a(25) =60138a(26) =69615a(27) =80591a(28) =92365a(29) =105865