4507889

Appears in sequences

• Odd integers n such that for every integer k>0, n*2^k-1 has a divisor in the set {3, 5, 7, 13, 17, 241}.at n=23A244070
• Odd numbers n not congruent to 1 mod 6 and that are not perfect powers such that for all k >= 1 the numbers n*4^k - 1 are composite.at n=27A251757