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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Claim. K. Benli, C. Dartyge, C. Dombrowsky, P. Pollack and L. Thompson, On the digits of the sum of proper divisors, arXiv:2607.18981 (v1, 21 July 2026), Theorem 1.4: "Fix g≥2g\geq2, γ∈(0,1)\gamma\in(0,1), and a nonempty set D⊊{0,1,…,g−1}\mathcal{D}\subsetneq\{0,1,\ldots,g-1\}. For all sufficiently large xx, the number of n≤xn\leq x for which s(n)s(n) has all of its digits in base gg restricted to digits in D\mathcal{D} is O(xexp⁡(−(log⁡log⁡x)γ))O(x\exp(-(\log\log x)^\gamma))" (result page). The paper cites the earlier Theorem 1.8 of Benli, Cesana, Dartyge, Dombrowsky and Thompson for g≥3g\ge3 and proves the case g=2g=2, omitted there, by a separate elementary argument in its Appendix A. It keeps the general assertion as its Conjecture 1.3 and says that it remains open.

Covers. The base-22 missing-digit targets, which the earlier theorem omits; with it, the missing-digit targets in every base g≥2g\ge2. The general assertion stays open.

Depends on. The 2023 missing-digit theorem for g≥3g\ge3.

Acceptance. Claimed: an arXiv preprint, with no refereed publication or curator credit on record.