Odd composite numbers k such that A053575(k) [the odd part of phi] divides k-1.

Terms

a(0) =15a(1) =51a(2) =85a(3) =91a(4) =255a(5) =435a(6) =451a(7) =561a(8) =595a(9) =771a(10) =1105a(11) =1261a(12) =1285a(13) =1351a(14) =1695a(15) =2091a(16) =2431a(17) =2465a(18) =3655a(19) =3855a(20) =4369a(21) =4795a(22) =5083a(23) =5151a(24) =5383a(25) =6601a(26) =6643a(27) =6735a(28) =7051a(29) =8245