a(n) = Sum_{k=1..n} k^2 * floor(n/k)^3.

Terms

a(0) =1a(1) =12a(2) =40a(3) =121a(4) =207a(5) =473a(6) =649a(7) =1142a(8) =1611a(9) =2401a(10) =2853a(11) =4647a(12) =5285a(13) =6879a(14) =8759a(15) =11452a(16) =12558a(17) =16739a(18) =18127a(19) =23353a(20) =27129a(21) =31171a(22) =33219a(23) =43573a(24) =47524a(25) =53210a(26) =59538a(27) =69996a(28) =73274a(29) =89694