330805domain: NAppears in sequencesNumbers n such that 6^phi(n) == 1 (modulo n^2), where phi(n) is Euler's totient function.at n=1A241978a(n) = smallest composite c such that n^(A000010(c)) == 1 (mod c^2), i.e., smallest composite Wieferich number to base n.at n=5A247154