Problem Statement
Are there infinitely many primes $p$ such that $p=2^kq+1$ for some prime $q$ and $k\geq 0$? Or $p=2^k3^lq+1$?
Categories:
Number Theory
Progress
This is mentioned in problem B46 of Guy's collection [Gu04].Source: erdosproblems.com/1065 | Last verified: January 19, 2026