arXiv:2008.09698v2

kk--Fibonacci numbers with two blocks of repdigits

Eric F. Bravo, Jhon J. Bravo, Carlos A. Gómez

math.NT11B3911J86

Abstract

A generalization of the well--known Fibonacci sequence is the kk--Fibonacci sequence with some fixed integer k2k\ge 2. The first kk terms of this sequence are 0,,0,10,\ldots,0,1, and each term afterwards is the sum of the preceding kk terms. In this paper, we find all kk--Fibonacci numbers that are concatenations of two repdigits. This generalizes prior results which dealt with the above problem for the particular cases of Fibonacci and Tribonacci numbers.

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Audited against latest accessible manuscript v1; current record v2

Not a correctness certificate. A “Correct” result may include yellow typos or minor formal corrections that do not affect substantive soundness. It means this audit found no unresolved substantive error under the stated criteria; it does not replace expert scrutiny or formal verification.

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Detailed mathematical audit

Generated August 15, 2026
01Statements1 reported findingCorrect

The classification in Theorem 1 is correct. A later independent paper proves the same classification for all terms with at least three digits, while the remaining one- and two-digit cases follow directly from the initial segment of the recurrence. This truth verdict is separate from the reproducibility limitation in the manuscript's own proof.

Theorem 1Correct

Classification of kk-Fibonacci numbers formed by two repdigit blocks

Pages 2–12 · Theorem 1 · arXiv:2008.09698v1

Alahmadi, Altassan, Luca, and Shoaib independently prove that the only such kk-generalized Fibonacci numbers having at least three digits are 144,233,377,773,2000,255,144,233,377,773,2000,255, and 511511, with exactly the indices and values listed here. For at most two digits, the recurrence gives the common power-of-two initial segment and the few next terms; direct substitution yields precisely the additional values and infinite families displayed in Theorem 1. Thus the statement itself is verified even though the present manuscript's decisive reduction computations are not reproducible from the information printed.

Alahmadi–Altassan–Luca–Shoaib, Theorem 1.1
02Proofs3 reported findingsContains unverified proofs

The analytic reductions and elementary recurrence arguments are internally consistent, but the decisive continued-fraction reductions and terminal searches are reported only as Mathematica outcomes. The supplied manuscript contains neither the convergents and epsilon certificates nor code or exhaustive output sufficient to verify those steps.

Dujella–Pethő reductionsNot able to verify

The decisive numerical hypotheses and maxima are not supplied

Pages 7–8 and 10–12 · Equations (15), (16), (22), and (27) · arXiv:2008.09698v1

Lemma 2 applies only after selecting a convergent with q>6Mq>6M and proving ε=μqMγq>0\varepsilon=\lVert\mu q\rVert-M\lVert\gamma q\rVert>0. The proof reports only the resulting bounds 151,501,950,1950,210,151,501,950,1950,210, and 450450. It does not identify the convergents, give the minimum positive ε\varepsilon over the parameter families, state the precision or exact-arithmetic method, or provide code. Several families have a varying μ\mu depending on d1,d2,k,d_1,d_2,k, and mm, so one displayed scalar assertion cannot be checked from the manuscript alone. Repair classification: No repair supplied; reproducible certificates or code covering every enumerated parameter tuple are required. The affected reductions are what exclude all remaining k>500k>500 cases and bound the small-kk search.

Dujella–Pethő reduction theorem cited by the manuscript
Finite searchesNot able to verify

The low-range and terminal enumerations have no verifiable certificate

Pages 4 and 8 · Equations (6)–(7) and lines following Lemma 5 · arXiv:2008.09698v1

The proof attributes both the initial enumeration and the final scan of Fn(k)F_n^{(k)} for 2k5002\leq k\leq500 and 5n5005\leq n\leq500 to an unspecified Mathematica routine. No routine, checksum, table, or independent finite certificate is included. The search domain is finite and the claimed output is consistent with the independently published classification, but the computation as part of this printed proof cannot be verified from the supplied material. Repair classification: Plausible repair only; publishing a short exact-integer enumeration and its output would make this step directly checkable.

Analytic reductionCorrect and complete

The symbolic estimates preceding the computations

Pages 5–10 · Lemmas 4 and 6 and Equations (8)–(20) · arXiv:2008.09698v1

The two Matveev applications give the displayed polynomial-exponential bounds in kk and nn, and the large-kk approximation converts the recurrence to a linear form in log10\log 10 and log2\log 2. The nonvanishing arguments, height bounds, and split according to min{k/2,mlog10/log2}\min\{k/2,m\log 10/\log 2\} have the required direction. No symbolic contradiction or omitted parameter regime was found before the numerical reductions.

03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:2008.09698v2
Authors listed
Eric F. Bravo, Jhon J. Bravo, Carlos A. Gómez
Audit date
August 15, 2026
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