525083

Appears in sequences

• Numbers n such that sigma(sigma(n) - phi(n)) = phi(sigma(n) + phi(n)).at n=22A074876
• Least number k such that between k! and (k+1)! there are n powers of 2 (each interval includes (k+1)! but not k!).at n=19A084321
• Number of edges in the n-Pell graph.at n=13A364553