216211domain: NPropertiesPrimalityPrimeyesAppears in sequencesSmallest odd prime number Q such that Q*2^P-1 is also prime with P Mersenne prime exponent A000043(n).at n=25A249383Primes p that set a new record for the size of the smallest b > 1 such that b^(p-1) == 1 (mod p^2).at n=42A287147Prime numbersat n=19303