Number k such that gcd(phi(k), k-1) = number of distinct prime factors of k.

Terms

a(0) =2a(1) =4a(2) =8a(3) =15a(4) =16a(5) =32a(6) =35a(7) =39a(8) =51a(9) =55a(10) =63a(11) =64a(12) =70a(13) =75a(14) =87a(15) =95a(16) =99a(17) =111a(18) =115a(19) =119a(20) =123a(21) =128a(22) =130a(23) =135a(24) =143a(25) =147a(26) =154a(27) =155a(28) =159a(29) =171