Open problem
Starting value 47 refutes Erdős's proposed unique counterexample
Erdős, Rocky Mountain Journal of Mathematics 15(2) (1985), page 361 (verbatim from the rendered scan at https://users.renyi.hu/~p_erdos/1985-27.pdf):
Put (21) ∏_{i=1}^{k} (x + i) = u_k(x) v_k(x), (u_k(x), v_k(x)) = 1 where v_k(x) is squarefree and all prime factors of u_k(x) occur with an exponent greater than 1. The representation in (21) is clearly unique. Clearly for k > k_0(x), u_k(x) > v_k(x). Perhaps one can estimate the smallest k_0(x) so that u_k(x) > v_k(x) for all k > k_0(x) quite well. I have not done this. For small values of k usually v_k(x) > u_k(x). I thought that for every x there is a k for which v_k(x) > u_k(x). x = 7 seemed a likely counterexample but if k = 7, u_7(7) = 2^7 3^3 < v_7(7) = 5·7·11·13. On the other hand a simple computation shows that n = 23 is a counterexample, i.e., for every k, v_k(23) < u_k(23). The reason for this is the existence of 24, 25, 27 and 32. I would not be surprised if 23 is the only counterexample. Perhaps in fact there is a k_0 so that for every k > k_0 and all n > n_0(k) (22) v_k(n) > u_k(n). (22) is perhaps too optimistic.
The literal refuted statement is
∀ x ≥ 1, x ≠ 23 → ∃ k ≥ 1, u(x,k) < v(x,k).
For P(x,k) = ∏_{i=1}^k (x+i), v(x,k) is the product of the
primes whose exponent in P(x,k) is exactly one. It is not the squarefree
part: a prime occurring to exponent at least two is absent from v.
The factor u(x,k) is the product of every prime power whose exponent in
P(x,k) is at least two, with its full exponent. Thus u(x,k)·v(x,k)=P(x,k).
The result refutes only the sentence proposing 23 as the unique
counterexample. It makes no claim about conjecture (22), an estimate of
k_0(x), the assertion that 23 and 47 are the only counterexamples, or the
statement that 23 itself is a counterexample.
Proof record
Module present in current Truth release; resolution evidence is pinned below.
D5/S3/Factorization/ErdosConsecutiveProductSquarefreeFactorRefutation.result
Evidence snapshot: b52262a023c4db9bb30a128ebfd80ea4ef4c1a53. The linked mdBook follows upstream development.