131681894401domain: NAppears in sequencesa(n) = (n!)^2 + 1.at n=9A020549Primes of the form (k!)^2 + 1.at n=5A051739Smallest prime factor of A020549(n) = (n!)^2 + 1.at n=9A282706Largest prime factor of A020549(n) = (n!)^2 + 1.at n=9A301346Primes of the form k!*m! + 1, with k <= m.at n=22A392757