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

Terms

a(0) =1a(1) =13a(2) =43a(3) =97a(4) =211a(5) =533a(6) =1133a(7) =2627a(8) =3907a(9) =4687a(10) =4801a(11) =11231a(12) =15689a(13) =33613a(14) =45995a(15) =82643a(16) =92543a(17) =106571a(18) =143903a(19) =156383a(20) =159947a(21) =173239a(22) =190399a(23) =370913a(24) =390247a(25) =393049a(26) =437747a(27) =487547a(28) =513193a(29) =519601