a(n) = Sum_{k=1..n} Sum_{d=1..k} (k mod d).

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =6a(6) =9a(7) =17a(8) =25a(9) =37a(10) =50a(11) =72a(12) =89a(13) =117a(14) =148a(15) =184a(16) =220a(17) =271a(18) =318a(19) =382a(20) =443a(21) =513a(22) =590a(23) =688a(24) =773a(25) =876a(26) =988a(27) =1113a(28) =1237a(29) =1388