a(n) = sigma_2(n) + phi(n) * sigma(n).

Terms

a(0) =2a(1) =8a(2) =18a(3) =35a(4) =50a(5) =74a(6) =98a(7) =145a(8) =169a(9) =202a(10) =242a(11) =322a(12) =338a(13) =394a(14) =452a(15) =589a(16) =578a(17) =689a(18) =722a(19) =882a(20) =884a(21) =970a(22) =1058a(23) =1330a(24) =1271a(25) =1354a(26) =1540a(27) =1722a(28) =1682a(29) =1876