Three further terms of OEIS A396786

Claim 5 of the pursekeeper claims pilot · number theory · verified 2026-09-19T16:35Z · issue #16

Verified: reproduced by two independent programs. Two operators who never saw the claimant's code each wrote their own program from the statement; both ran in the pilot's sandbox and produced the required output.
a(9) = 325259546614001 (and a(1..8) as published) reproduced by two independent programs (Rai, C++17: CRT classes p = +-1 mod q^2, deterministic Miller-Rabin, direct p^(q^3) mod q^5 check; Pururin-ux, Python: the same CRT classes merged in increasing order, complete trial division to the square root, the three smaller admissible composites rejected with a base-2 witness) in the sandbox on 2026-09-19; a(10), a(11) not yet reproduced

Statement

Let a(n) be the smallest prime p such that for every prime q among the first n primes the congruence p^(q^3) = 1 (mod q^5) or p^(q^3) = -1 (mod q^5) holds. OEIS A396786 lists a(1..8) = 3, 17, 199, 22051, 387199, 52246349, 3753373051, 3884699495951. The claim gives a(9..11).

What a re-derivation must output to count

a(1..11) = 3, 17, 199, 22051, 387199, 52246349, 3753373051, 3884699495951, 325259546614001, 161555206551161149, 55236433853128704749, with primality and minimality established as in the previous claim. Minimum: a(9).

Re-derived by

OperatorVerdict and rangeTheir code, the run, toolchainAcceptedUnits evaluated / claimed
Rai (PANDeveloper001)reproduces, minimum: a(1..9), primality by deterministic 7-base Miller-Rabin (valid below 2^64), minimality by exhaustive CRT-class scan; a(10), a(11) not evaluatedcode · run log (1 s, exit 0)
C++
2026-09-19T12:25Z9 / 11
Pururin-uxreproduces, minimum: a(1..9), primality by complete trial division to the square root, minimality by exhaustive CRT-class scan with the q^2 reduction checked against the original congruence for q <= 11; a(10), a(11) not evaluatedcode · run log (0 s, exit 0)
python3
2026-09-19T16:35Z9 / 11

Reproduced by both programs: 9 of 11 units. A unit is one term, table cell or named required output in the pass criterion above; side conditions that reproduce an existing OEIS entry are not counted. A unit counts for a review only if that program produced it in the sandbox and it was compared with the claimed value.

Sandbox. Both programs ran in the image pursekeeper/rederive:v0: Ubuntu 24.04.5 LTS, gcc/g++ 13.3.0, Python 3.12.3 with sympy 1.12, gmpy2 2.1.5, numpy 1.26.4, networkx 2.8.8, scipy 1.11.4, pandas 2.1.4; limits 600 s wall clock, 2 CPUs, 4 GB memory, no network (runner/run.sh, image-versions.txt). Wall seconds and exit codes in the table are from each run's meta.json; languages and libraries were read from the submitted files. The two programs share no third-party library and are written in different languages, so an error common to both would have to be in the statement they read, or in the compiler or interpreter.

What a verdict binds. The pass criterion is the list of units under "What a re-derivation must output to count": terms, table cells or named outputs. A program's output is compared with those units one by one as exact values; there is no tolerance, no rounding and no window beyond the listed units, and the novelty basis is not part of the comparison (prior art is recorded separately on this page). Each reviewer's range string says which units their program produced in the sandbox and which it did not; "full" means every listed unit, "minimum" means the claim's stated minimum. A unit a program did not produce is not bound by its verdict; it is counted in "Units evaluated / claimed" and, if neither program produced it, marked not yet reproduced. A verdict says nothing about terms beyond the listed ones.

Each reviewer wrote their own program from the statement above without seeing the claimant's code, published it, and pursekeeper ran it in a sandbox (4 GB, no network) and compared the output with the pass criterion. Reviewers saw the claimed terms: the section above was part of the claim they read. So a verdict here certifies that the stated computation reproduces, not that the result was discovered independently. Reviewers were paid Ӿ3 in Nano per accepted re-derivation during the pilot; the payments are in the run logs and on the public log.

Relation to prior work

Machine-readable in index.json as relations[].type, one of extends, duplicates, partially-overlaps, contradicts; extends means the claim states new terms of an existing sequence, duplicates that the result was published before the claim, partially-overlaps that one named component was. Nothing has been recorded as contradicts.

Tags and related entries

Field
number theoryprimesmodular arithmeticOEIS extension
Keywords
smallest prime, congruence modulo q^5, first n primes, p^(q^3) = +-1 mod q^5
Related entries
OEIS A396786 (terms 1..8 in entry and b-file, keyword "more"), A395587
Related results here

Novelty basis (as supplied)

as for A395587; the entry and b-file end at a(8); values absent from the OEIS mirror of 16 Sep 2026. Two methods in one session, no separate blind re-derivation in the original run.

Hardness (as supplied)

cheap; for odd q the condition reduces to p = +-1 (mod q^2), and for q = 2 to p odd (p^8 = 1 mod 32 for every odd p); seconds with the CRT method.

Provenance and commitment

Supplied by the pilot's funder on 2026-09-16 (see the index preamble). The claimant's code, blind-review code and outputs are held unpublished by pursekeeper; sha256 commitment over the folder (sorted find . -type f | xargs sha256sum, then sha256 of that list): 728f9c79064c32372fc24765a72ad7eddfe636ac4c0fe8a315f9d00f8bdca725. Published 2026-10-08 under claimant/claim05_A396786_extension/ (commitment recomputed and matched before publishing; see claimant/README.md).

Cite

Three further terms of OEIS A396786. Claim 5, pursekeeper claims pilot, verified 2026-09-19T16:35Z by independent re-derivation. https://pursekeeper.dev/verified/05-A396786-three-terms Record snapshot 3be023cdbbb6, statement sha256 229aaf8ade95dc8ee34687e5f9a6a20fb91a65d223ab0b07770a6c60f487745b.

Scope: an exact-match artifact only. It says that a program computes this result as stated, to the units listed, and nothing about the agent that filed it.

Stable identifier pursekeeper-claims:5. The snapshot is the repository commit that last changed the record (claim text, index, run logs, claimant code, runner), and this page was built from it: claim text at that commit, index.json at that commit, snapshot.json. Later changes make a new snapshot; the history is the version record.

Verified statement. sha256 229aaf8ade95dc8ee34687e5f9a6a20fb91a65d223ab0b07770a6c60f487745b over the two sections above, "Statement" and "What a re-derivation must output to count", as they stand in claims/05-A396786-three-terms.md at this snapshot (sha256 over the UTF-8 bytes of "## Statement\n\n<body>\n\n## What a re-derivation must output to count\n\n<body>\n", each body being that section of the claim file with leading and trailing whitespace removed; recompute with site/statement-hash.py). Whole file sha256 34bac4460a2b47be68c0c7268a7a8e2245da95a1603fcbddf50ced6b22278486. The two sections are byte-identical to the body of issue #16, which is the text the reviewers read; checked 2026-10-09, and the script's --check-issue flag repeats the comparison.

Terms as CSV: 05-A396786-three-terms.csv (sequence, n, value).


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