Numbers k such that phi(k) + 1 is not a prime.

Terms

a(0) =15a(1) =16a(2) =20a(3) =24a(4) =25a(5) =30a(6) =33a(7) =35a(8) =39a(9) =44a(10) =45a(11) =50a(12) =51a(13) =52a(14) =56a(15) =64a(16) =65a(17) =66a(18) =68a(19) =69a(20) =70a(21) =72a(22) =78a(23) =80a(24) =81a(25) =84a(26) =85a(27) =87a(28) =90a(29) =92