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

Terms

a(0) =1a(1) =2a(2) =8a(3) =12a(4) =128a(5) =240a(6) =350a(7) =366a(8) =368a(9) =575a(10) =671a(11) =720a(12) =743a(13) =1098a(14) =2417a(15) =6912a(16) =18967a(17) =19399a(18) =32768a(19) =142560a(20) =173340a(21) =179010a(22) =184032a(23) =188892a(24) =203310a(25) =209628a(26) =225342a(27) =228582a(28) =232160a(29) =244782