Numbers k such that phi(sigma(k)) = 3*phi(k).

Terms

a(0) =4a(1) =12a(2) =30a(3) =50a(4) =60a(5) =90a(6) =120a(7) =150a(8) =180a(9) =200a(10) =225a(11) =360a(12) =390a(13) =444a(14) =528a(15) =600a(16) =672a(17) =700a(18) =714a(19) =732a(20) =876a(21) =1110a(22) =1170a(23) =1332a(24) =1428a(25) =1560a(26) =1584a(27) =1830a(28) =1884a(29) =1920