Numbers n such that sigma(phi(n))/sigma(n) = 2.

Terms

a(0) =13a(1) =71a(2) =89a(3) =203a(4) =305a(5) =319a(6) =667a(7) =1363a(8) =1421a(9) =1525a(10) =1711a(11) =1889a(12) =2407a(13) =2933a(14) =3103a(15) =4609a(16) =4615a(17) =4843a(18) =5191a(19) =6583a(20) =7123a(21) =7625a(22) =7627a(23) =9947a(24) =10063a(25) =10411a(26) =11107a(27) =13543a(28) =13891a(29) =14587