Numbers n for which sigma(sigma(n)) = 3*sigma(n).

Terms

a(0) =54a(1) =56a(2) =87a(3) =95a(4) =276a(5) =308a(6) =429a(7) =446a(8) =455a(9) =501a(10) =581a(11) =611a(12) =158928a(13) =194928a(14) =195072a(15) =199950a(16) =226352a(17) =234608a(18) =236432a(19) =248325a(20) =255678a(21) =263504a(22) =266192a(23) =273050a(24) =275415a(25) =304575a(26) =336903a(27) =341162a(28) =353675a(29) =366575