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

Terms

a(0) =1a(1) =13a(2) =71a(3) =87a(4) =89a(5) =181a(6) =203a(7) =305a(8) =319a(9) =362a(10) =667a(11) =899a(12) =1257a(13) =1363a(14) =1421a(15) =1525a(16) =1711a(17) =1798a(18) =1889a(19) =2407a(20) =2501a(21) =2933a(22) =3103a(23) =4609a(24) =4615a(25) =4687a(26) =4843a(27) =5002a(28) =5191a(29) =6583