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

Terms

a(0) =0a(1) =2a(2) =7a(3) =17a(4) =29a(5) =51a(6) =71a(7) =104a(8) =138a(9) =183a(10) =220a(11) =293a(12) =340a(13) =409a(14) =486a(15) =580a(16) =646a(17) =767a(18) =843a(19) =981a(20) =1099a(21) =1221a(22) =1317a(23) =1525a(24) =1653a(25) =1802a(26) =1961a(27) =2168a(28) =2297a(29) =2568