Plectis

Long paper

Reciprocal Mersenne Subseries

Summary. A weighted summability criterion proves irrationality of reciprocal Mersenne subseries: if h is the part of a supported on a finite nonempty prime set P, every infinite A with ∑ h(a)/(a(bh(a)−1)) finite has irrational ∑ (ba−1)−1. The base-two condition gives the conclusion at every integer base for every infinite subset, and permits an example with divergent reciprocal sum, while excluding full support and all odd exponents. The proof averages over a finite part of the support and over dyadic observation lengths. Erdős's weaker reciprocal-summable theorem is proved in full, and a common window extends both arguments to unions of weighted and positive-cover supports. Finite-denominator and achievement-set calculations formulate tests for the targets 1/2 and 1/21; those tests do not decide either target or the universal question. Prime support at base 2 and squarefree support at power-of-two bases are attributed as existing work.

This paper covers a claim-bounded problem-specific reasoning surface for Erdős #257: selected checked premises, finite computations, closed routes, surviving obligations, and their exact evidence bands.

It does not establish the validity of claims tagged Lean, which belongs to the cited kernel-checked source, or a solution to Erdős #257, whose universal and half-value questions remain open.

In this paper
Reported finite checks

The following values and finite ranges come from exact integer computations for the quotient-greedy sequence of Section 5.4. They provide test cases for the formulas above. The low-row remainders at n=14,15,32 are exact integer values. Each larger certified range has a published program and saved run.

Observation 5.17 (Exact low-row values). At row n=14: rem(14)=392, with take set D14={2,3,6,7}. At row n=15: rem(15)=34333. At row n=32: rem(32)=3865046005 and Δ32=−429921291.
Source: the values at rows 14–31 are proved in Lean by direct evaluation (Theorem 6.10), which uses them to verify the band-escape condition for reset indices 13≤d≤30 seamUpperResetDyadicBandEscape_through_thirty. The two ranges differ by one: the remainder used for reset d is at row d+1. The take set D14, rem(32) and Δ32 are exact integer computations with the greedy rule of Section 5.4.

Observation 5.18 (Depths of the reported computations). The quotient identity (Theorem 5.14) is verified at rows 6≤n≤200 with zero mismatches (saved run), and the quotient-greedy orbit itself is certified row by row to row 2500 (saved run) and through the exact branch recursion to row 200,000 (saved run; branch counts R:M:U=100197:49899:49898, the target inequality failing at exactly one reset row 6≤r≤200,000, namely r=7).

Observation 5.19 (Four computations side by side). Four related computations are reported, with different targets or integer representations, at the following ranges: truncation rung J=3,…,22 (all 20 rungs proved to survive, not merely computed); quotient row 6≤n≤2500 (Theorem 5.14 and the branch data underlying Theorem 5.16); integer margin scan to mc=5×105 (an exploratory scan, which is not certified); sharp tail margin, ranks 2 through 3000 (no fatal skip at any rank; take fraction 0.4992; tightest certified take-margin 0.0340 bits at rank 7, the near-tie 1/126≥1/127).
Use: truncated weights define a different greedy problem, and the quotient-row construction uses integer weights rather than the original real weights. These are not automatically four readings of the same decision stream. Their relevance to full-weight membership comes from the approximation, limit, or identification theorems cited for each construction. A certificate at one range does not transfer to another without such a theorem, and these reports do not decide the universal problem.

About this paper

Authorship and AI use. Will Cook built and directed the research infrastructure and maintains the public release. He reviewed claims when he could. AI agents did most of the research and drafting. Cook did not independently verify every claim.

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