150121

Appears in sequences

• Numbers n such that sigma(phi(n))/sigma(n) = 3.at n=22A067383
• Composite numbers k such that k divides F(k-1) where F(j) are the Fibonacci numbers.at n=33A069106
• Numbers k that divide Fibonacci(k-1) but do not divide Fibonacci(k) - 1.at n=17A094410