27606810

Appears in sequences

• a(n) is the smallest number k such that psi(k) = n*phi(k) where psi(k) is Dedekind psi function (A001615) and phi(k) is Euler totient function (A000010), or 0 if no such k exists.at n=18A291051
• a(n) is the smallest k such that psi(k)/phi(k) is prime where k is the product of n distinct primes.at n=7A291972