Even numbers k such that phi(k) and k-1 are distinct and have a common factor > 1.

Terms

a(0) =28a(1) =52a(2) =66a(3) =70a(4) =76a(5) =112a(6) =124a(7) =130a(8) =148a(9) =154a(10) =172a(11) =176a(12) =186a(13) =190a(14) =196a(15) =208a(16) =232a(17) =238a(18) =244a(19) =246a(20) =268a(21) =276a(22) =280a(23) =286a(24) =292a(25) =304a(26) =310a(27) =316a(28) =322a(29) =344