39268347319domain: NAppears in sequencesa(n) is the maximal overpseudoprime q to base 2 such that the multiplicative order of 2 mod q equals A143584(n).at n=20A131952Numbers of the form (2^(p*q)-1) /((2^p-1)*(2^q-1)), where p>q are primes.at n=16A140803Numbers of the form (4^p + 2^p + 1)/7, where p > 3 is prime.at n=5A143012