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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Claim. Jens Kruse Andersen posted on Prime Puzzles problem 27 on 4 May 2007 the least primes admitting kk adjacent intervals of consecutive integers whose products are each 11 modulo pp, for k=10,…,14k=10,\ldots,14: 2790127901, 5216352163, 778699778699, 23746492374649 and 1042800710428007, each with its intervals. For k=14k=14 the intervals are [816489,1251081][816489,1251081], [1251082,3384225][1251082,3384225], [3384226,4112650][3384226,4112650], [4112651,4237275][4112651,4237275], [4237276,4431559][4237276,4431559], [4431560,4467010][4431560,4467010], [4467011,4835062][4467011,4835062], [4835063,7328694][4835063,7328694], [7328695,7385077][7328695,7385077], [7385078,7415726][7385078,7415726], [7415727,8460938][7415727,8460938], [8460939,8689396][8460939,8689396], [8689397,9295594][8689397,9295594] and [9295595,9661614][9295595,9661614], modulo the prime 1042800710428007. The method is a search over the residues q! mod pq!\bmod p for q<pq<p: if q1!≡q2!≢0q_1!\equiv q_2!\not\equiv0, the product over (q1,q2](q_1,q_2] is 11 modulo pp, and a residue occurring k+1k+1 times gives kk adjacent intervals. A direct computation confirms that 1042800710428007 is prime and that all fourteen products are 11 modulo it. The first kk of these intervals form a witness for each kk from 22 to 1414.

Andersen submitted the five primes to OEIS A060427, whose terms run through a(14)=10428007a(14)=10428007; the entry, created by Jason Earls in 2001, lists only the least primes. The smaller cases on the same Prime Puzzles page are C. Rivera's recomputation of the least primes for k≤9k\le9 (1111, 1717, 2323, 7171, 599599 and 30113011), following Landon Curt Noll's submission of the problem to the site in 1999. A forum post by Kenta Kitamura of 21 June 2026, prepared with the assistance of Codex 5.5 and ChatGPT 5.5 Pro, restates the k=14k=14 witness as fifteen factorials congruent to 89789988978998 modulo 1042800710428007 and the fourteen intervals they bound; it is a thread post restating this result and has no page of its own.

Covers. Every case 2≤k≤142\le k\le14 of Problem 1056: such a prime exists for each of these kk, under the sources' reading recorded in the problem page's Formulation.

Standing. Claimed. The witnesses are finite computations, but they were posted on a puzzle site and in the OEIS, with no review or refereed publication recorded, and the site labels the problem OPEN. Nothing here is independently reviewed by this project.