Let p1=2,p2=3,p3=5,…,pk be the first k primes. For positive integers x and nonnegative integers α1,…,αk, consider the Diophantine equation
x2−1=p1α1⋯pkαk.
Dąbrowski's conjecture. The equation has exactly 28 solutions (x;α1,…,αk) in positive integers, namely the solutions listed in the statement: (3;3); (5;3,1),(7;4,1),(17;5,2); (11;3,1,1),(19;3,2,1),(31;6,1,1),(49;5,1,2),(161;6,4,1); (29;3,1,1,1),(41;4,1,1,1),(71;4,2,1,1),(251;3,2,3,1),(449;7,2,2,1),(4801;7,1,2,4),(8749;3,7,4,1); (769;9,1,1,1,1),(881;5,2,1,2,1),(1079;4,3,1,2,1),(6049;6,3,2,1,2),(19601;5,4,2,2,2); (3431;4,1,1,3,1,1),(4159;7,3,1,1,1,1),(246401;8,6,2,1,1,2); (1429;3,1,1,1,1,1,1),(24751;5,2,3,1,1,1,1),(388961;6,4,1,4,1,1,1); and (1267111;4,3,1,1,3,1,1,2).
This conjecture asks for a complete determination of the solutions whose value x2−1 has no prime factors beyond the first k primes. The source attributes the formulation to Dąbrowski; the provided text gives no evidence that the conjecture has been proved or disproved.