EN
Let $p_i$ denote the ith prime. We conjecture that there are precisely 28 solutions to the equation $n² - 1 = p₁^{α₁} ⋯ p_k^{α_k}$ in positive integers n and α₁,..., $α_k$. 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).