399126

Appears in sequences

• Numbers n such that sigma(n) = 11*phi(n) (where sigma=A000203, phi=A000010).at n=12A171257
• Number of Cayley graphs on n nodes.at n=44A185959
• a(1) = 1; for n > 1, a(n) = smallest integer > a(n-1) such that a(n)*a(i)+1 is semiprime for all 1 <= i <= n-1.at n=12A219953
• 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=5A291972