12379533domain: NAppears in sequencesLeast k such that (2*p_n)*k + 1 | Mersenne(p_n), p_n = n-th prime, n >= 2.at n=25A016048k such that 2kp+1 is the first factor of a nonprime Mersenne number M(p) = 2^p - 1.at n=16A079324