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

Terms

a(0) =1a(1) =108a(2) =135a(3) =196a(4) =245a(5) =297a(6) =539a(7) =810a(8) =1008a(9) =1176a(10) =1575a(11) =1782a(12) =1917a(13) =3056a(14) =3213a(15) =4464a(16) =6897a(17) =6944a(18) =7560a(19) =8820a(20) =9450a(21) =10017a(22) =11502a(23) =14229a(24) =16632a(25) =16821a(26) =18009a(27) =18336a(28) =19278a(29) =19404