Existence of arbitrarily deep preperiod reductions if the lower-bound conjecture fails
Determine whether the following implication holds: if there exist an odd prime p and an integer r≥2 with s(p^r)<r−2, then for every integer k≥3 there exist an odd prime p and an integer r≥k such that s(p^r)=r−k.
References
If Conjecture~\ref{conj:preperiod-lower} is false, then for every integer k\ge3 there exist an odd prime p and an integer r\ge k such that s(pr)=r-k. We leave this conjecture as an open problem.
— Modular periodicity of the Euler up/down numbers at odd prime powers
(2608.27058 - Güleç, 27 Aug 2026) in Section 5, Computational remarks, immediately after Conjecture 5.5