310845

Appears in sequences

• Odd composite numbers k such that cototient(k) - phi(k) = k - 2*phi(k) is an odd prime.at n=19A083255
• Numbers n such that cototient(n) does not divide phi(n!).at n=8A291597
• Terms of A051488 that do not belong to A083207.at n=12A333232