59236domain: NAppears in sequencesNumbers n such that 257*2^n-1 is prime.at n=27A050887a(1) = 1, for n >= 2, a(n) = Sum_{i=1..floor(log_2(n))} a(n-i).at n=20A306622Number of mutual-visibility sets in the n-web graph.at n=5A389188