Numbers k such that phi(x) = k has exactly 3 solutions.

Terms

a(0) =2a(1) =44a(2) =56a(3) =92a(4) =104a(5) =116a(6) =140a(7) =164a(8) =204a(9) =212a(10) =260a(11) =296a(12) =332a(13) =344a(14) =356a(15) =380a(16) =392a(17) =444a(18) =452a(19) =476a(20) =524a(21) =536a(22) =564a(23) =584a(24) =588a(25) =620a(26) =632a(27) =684a(28) =692a(29) =716