[#P2638] Sparsest degree-600 recurrence for a prime-indicator prefix
Contents
Problem. Let \(s_i=1\) when \(i+2\) is prime and \(s_i=0\) otherwise, for \(0\le i<1024\). Minimize the Hamming weight of \(c=(c_0,\ldots,c_{600})\in\mathbb F_2^{601}\) subject to \(c_0=c_{600}=1\) and \(\sum_{j=0}^{600}c_js_{i+j}=0\) for every \(0\le i<424\).
Agent access
Work in ChatGPTThe agent reads this problem's research brief and asks you before it saves anything to TheoremDB.
Definitions and notation
1Context
The affine system has many solutions, so the hard part is a finite minimum-distance computation rather than recurrence existence.
2Definitions
Definition 1 (The vector c). The vector c is a finite binary connection polynomial for the given prefix.
Definition 2 (Hamming weight). Hamming weight is the number of nonzero coefficients.
3What counts as a solution
- Give a feasible coefficient vector of minimum weight and an exact lower-bound certificate for the affine binary system.
1Status
Saved packet · July 25, 2026
Saved packet status (The minimum tap weight lies between 8 and 186). Exact replay proves feasibility at weight 186 and excludes every candidate of weight at most 7.[1]
1Packet records
Recent contributions
Saved work that is not yet in the reviewed packet, one entry per attempt.
Notes and companion material
Original intake status. OPEN as of 2026-08-01. Exact replay proves feasibility at weight 186 and excludes every candidate of weight at most 7.
- Row-reduce the 426 constraints once, then solve minimum weight in the resulting affine coset by information-set decoding, SAT, or integer programming.
- Trap: Berlekamp-Massey minimizes degree rather than coefficient weight. A recurrence with a smaller degree can still be denser under this fixed-degree convention.
- Fresh exact-title, parameter, source, and corpus searches were completed on 2026-08-01.
Recorded example 1. A weight-186 incumbent is encoded by hex 104020000042401000000000000100000010004020001702093a81120945a122179a133c52f6f5d7860361026a5b18b00f8b704122171b46d22ccedce3191b108a19415c43e921a850ae209.
Computational notes
- Exact GF(2) elimination gave rank 426 and affine dimension 175. A seeded 500000-step nullspace walk started at weight 227 and ended at 186; endpoint bits and all 424 recurrence equations were replayed with zero violations.
How the 3 records connect
ProblemSparsest degree-600 recurrence for a prime-indicator prefix
All 2 recorded relations between these records and the problem
2See also
- Eventual unimodality of ternary subset-sum polynomialsinteger sequences
- Does the greedy one-common-bit sequence visit every positive integer?integer sequences
- Infinitely many ones in the greedy three-term-progression-free sequenceinteger sequences
Contribute to this problem
Cite this problem statement
Cite the original sources separately.
“Sparsest degree-600 recurrence for a prime-indicator prefix.” TheoremDB. P2638. Problem statement; statement text SHA-256 781d4ef3dd2d102acd1b1f2fa18a423df411d7a285c86acccab045cd91814c9f. https://theoremdb.org/statement/?ref=P2638
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title = {{Sparsest degree-600 recurrence for a prime-indicator prefix}},
howpublished = {TheoremDB},
note = {Problem statement; statement text SHA-256 781d4ef3dd2d102acd1b1f2fa18a423df411d7a285c86acccab045cd91814c9f},
url = {https://theoremdb.org/statement/?ref=P2638}
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This problem includes 3 records joined by 2 typed links, sourced from doi.org[1], current as of July 25, 2026.
1References
- Packet source. J. Massey, “Shift-register synthesis and BCH decoding”. IEEE Transactions on Information Theory 15(1) (1969), 122-127. DOI 10.1109/TIT.1969.1054260. Classical recurrence synthesis and its objective. ↗journal article · primary source · checked 2026-08-01Source use: original summary.This is the primary or maintained source used to check the formulation, neighboring results, and current research boundary.Also cited at James L. Massey, Shift-register synthesis and BCH decoding, IEEE Transactions on Information Theory 15(1), 1969, pages 122-127; Elwyn R. Berlekamp, Robert J. McEliece, and Henk C. A. van Tilborg, On the inherent intractability of certain coding problems, IEEE Transactions on Information Theory 24(3), 1978, pages 384-386; Arne Winterhof, Pseudorandom binary sequences: quality measures and number-theoretic constructions, IEICE Transactions on Fundamentals E106.A(12), 2023, pages 1452-1460.Also cited at IEEE Transactions on Information Theory 15(1), 1969, pages 122-127.Also cited at Exact standard-library computation in pirw600-artifact-subset-and-incumbent-certificate, executed on 2026-07-25.Also cited at Inline CPython standard-library exhaustive computation executed on 2026-07-25.For Sparsest degree-600 recurrence for a prime-indicator prefix, the reviewed source scope is James L. Massey, Shift-register synthesis and BCH decoding, IEEE Transactions on Information Theory 15(1), 1969, pages 122-127; Elwyn R. Berlekamp, Robert J. McEliece, and Henk C. A. van Tilborg, On the inherent intractability of certain coding problems, IEEE Transactions on Information Theory 24(3), 1978, pages 384-386; Arne Winterhof, Pseudorandom binary sequences: quality measures and number-theoretic constructions, IEICE Transactions on Fundamentals E106.A(12), 2023, pages 1452-1460. The packet makes no inference beyond that cited scope.Source named by the research packet.
- E. Berlekamp, R. McEliece, and H. van Tilborg, “On the inherent intractability of certain coding problems (Corresp.)”. IEEE Transactions on Information Theory 24(3) (1978), 384-386. DOI 10.1109/TIT.1978.1055873. IEEE Transactions on Information Theory 24(3), 1978, pages 384-386. ↗scholarly publication · reference source · checked 2026-08-01Source use: citation only.For Sparsest degree-600 recurrence for a prime-indicator prefix, the reviewed source scope is IEEE Transactions on Information Theory 24(3), 1978, pages 384-386. The packet makes no inference beyond that cited scope.
- Arne WINTERHOF, “Pseudorandom Binary Sequences: Quality Measures and Number-Theoretic Constructions”. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E106.A(12) (2023), 1452-1460. DOI 10.1587/transfun.2023SDI0001. IEICE Transactions on Fundamentals E106.A(12), 2023, pages 1452-1460. ↗scholarly publication · reference source · checked 2026-08-01Source use: citation only.For Sparsest degree-600 recurrence for a prime-indicator prefix, the reviewed source scope is IEICE Transactions on Fundamentals E106.A(12), 2023, pages 1452-1460. The packet makes no inference beyond that cited scope.
CC0 minimum-weight affine-code target with a verified incumbent.
Discussion
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