a(n) = n^2*Product_{p|n} (1 + 1/p).

Terms

a(0) =1a(1) =6a(2) =12a(3) =24a(4) =30a(5) =72a(6) =56a(7) =96a(8) =108a(9) =180a(10) =132a(11) =288a(12) =182a(13) =336a(14) =360a(15) =384a(16) =306a(17) =648a(18) =380a(19) =720a(20) =672a(21) =792a(22) =552a(23) =1152a(24) =750a(25) =1092a(26) =972a(27) =1344a(28) =870a(29) =2160