On perfect powers in products with terms from arithmetic progressions
Let denote the ith prime. We conjecture that there are precisely 28 solutions to the equation in positive integers n and α₁,..., . This conjecture implies an explicit description of the set of solutions to the Brocard-Ramanujan equation. We also propose another variant of the Brocard-Ramanujan problem: describe the set of solutions in non-negative integers of the equation n! + A = x₁²+x₂²+x₃² (A fixed).
Let be an odd prime. By using the elementary methods we prove that: (1) if , the Diophantine equation has no positive integer solution except when or is of the form , where is an odd positive integer. (2) if , , then the Diophantine equation has no positive integer solution.