a(n) = Sum_{k=1..n} k*d(k) where d(k) is the number of divisors of k.

Terms

a(0) =1a(1) =5a(2) =11a(3) =23a(4) =33a(5) =57a(6) =71a(7) =103a(8) =130a(9) =170a(10) =192a(11) =264a(12) =290a(13) =346a(14) =406a(15) =486a(16) =520a(17) =628a(18) =666a(19) =786a(20) =870a(21) =958a(22) =1004a(23) =1196a(24) =1271a(25) =1375a(26) =1483a(27) =1651a(28) =1709a(29) =1949