English

Primes in LCM recurrences

Number Theory 2026-04-22 v3

Abstract

We study an LCM-based analogue of Rowland's GCD-based prime-generating recurrence, introduced by the author in 2008. The multiplicative increments of this sequence are conjectured always to be 11 or prime, but a complete proof requires a strengthening of Linnik's theorem on the least prime in an arithmetic progression that lies beyond current reach. We develop a Companion--Sieve framework that reduces the conjecture to an equidistribution problem for primes in the progression 1modp-1\bmod p, and applying the Bombieri--Vinogradov theorem we prove unconditionally that the conjecture holds for a set of integers of asymptotic density 11. We also give an effective finite reduction showing that any counterexample beyond a computable threshold involves only large prime factors. A closely related recurrence turns out to encode twin prime pairs through its increment pattern, and we prove a conditional density-11 result for it under a prime-index detection hypothesis, using an upper-bound Selberg sieve estimate for twin primes in arithmetic progressions. The analysis also leads to three new conjectures on the distribution of primes in arithmetic progressions.

Keywords

Cite

@article{arxiv.2510.18891,
  title  = {Primes in LCM recurrences},
  author = {Benoit Cloitre},
  journal= {arXiv preprint arXiv:2510.18891},
  year   = {2026}
}

Comments

v3, 25 pages. Minor changes and use of Selberg sieve

R2 v1 2026-07-01T06:58:24.153Z