134053domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumbers k such that 19*2^k - 1 is prime.at n=26A001775Number of permutations of length n that avoid the patterns 321, 1342, 4123.at n=19A116714Primes of the form 2m*691 - 1.at n=19A134671Prime numbersat n=12500