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
What the experiments and obstructions do not imply

Everything in this subsection is inference from the recorded failures, not a theorem. Where the evidence does not determine the answer, the text says so.

Finite observations and their limits

The recorded obstructions concern specified representations. Fixed precision, a bounded carry state and a prescribed suffix can lose information needed by the actual-selector condition. They do not show that the underlying deterministic sequence has no arithmetic structure. The relevant exact statements remain fixedPrecisionTropicalNoGo, balancedPulse_no_autonomous_decoder and affineBinaryOrbit_mod_twoPow_eq. Their hypotheses, rather than the fact that an attempted argument failed, determine their scope.

The inherited experiment log reports 200,000 seam rows with counts R:M:U=100197:49899:49898, which a saved run reproduces, a roughly geometric run-length histogram, and a longest equal run of 15 in 40,000 binary digits. It also reports agreement with OEIS A211706 and a near-integer phase constant of about 2.5. The other figures and the external digit comparison come from that log alone. They are descriptive reports, not certificates of normality, independence, a random sampling model, or an infinite anti-concentration estimate. A statement about “sampling noise” would require a specified probabilistic model that is not supplied here.

The exceptional row r=7 and the crossing (s,d)=(10,7) are likewise statements about the tested ranges only: reset rows 6≤r≤200,000 and rows s≤2500 (saved run). No claim that this is the only exceptional row of the infinite orbit is made.

These representations all descend from the same greedy carry; they are not independent tests of a common random hypothesis. Strict tail domination gives an injective coding, but says neither that its digits are random nor that averaging over indices is impossible. The measure-one and nowhere-dense properties of the achievement set do not decide membership of a specified rational. The correct research question is whether a precise arithmetic estimate can be proved for the actual selector, not whether finite data resemble a random model.

Why the support and rational-target problems remain distinct

Proposition 11.4 is a reason to separate the two halves rather than assimilate them. On the universal side the present certificate method first meets a parity obstruction that depends on the choice of support. The squarefree value is nevertheless already known to be irrational at power-of-two bases, and adjoining 1 removes the opening-block obstruction without changing irrationality. Thus the obstruction concerns this method; it does not concern the value or the universal problem.

Short-window near-integer anti-concentration is one possible missing input for the particular mechanisms analysed here. No equivalence shows that it is necessary for either problem, and no argument identifies it as a common necessary obstruction to both. The squarefree example shows why finite rational changes of support must be checked before an opening-block failure is interpreted as a property of the value.

What the evidence does and does not determine

It does not determine whether a short proof exists: nothing in a catalogue of failed methods bounds the length of a successful one.

It records limitations of specified methods. The fixed-precision completion theorem and the balanced-pulse countermodel concern the particular summaries defined above, not all fixed-precision arithmetic or all finite-state methods with additional arithmetic input. An irrationality-measure bound on E does not classify a specified rational in A. Instantiating the present block-certificate method at a general support is blocked, on the universal side, by Proposition 11.4. Survival through any tested finite depth does not by itself establish membership; a fatal-gap certificate would establish non-membership. These facts do not decide rational-target membership, and they do not yield an impossibility theorem for all probabilistic, measure-theoretic or averaging methods.

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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