Odd composite n such that phi(n) * sigma(n) is one less than a square.

Terms

a(0) =33a(1) =69a(2) =295a(3) =423a(4) =451a(5) =531a(6) =581a(7) =1119a(8) =2893a(9) =4043a(10) =4163a(11) =4257a(12) =4509a(13) =5975a(14) =12977a(15) =14927a(16) =15753a(17) =19105a(18) =25369a(19) =27225a(20) =38013a(21) =38799a(22) =39771a(23) =85675a(24) =98531a(25) =157375a(26) =217349a(27) =264439a(28) =324643a(29) =330977