[seqfan] Re: Problem
W. Edwin Clark
wclark at mail.usf.edu
Fri Jul 24 23:14:22 CEST 2020
For the prime p = 94603 and for n from 1 to 100000, (p+1) 2^n - 1 is
composite, says Maple.
This prime appears twice in the OEIS if you don't count A094603. See
http://oeis.org/search?q=94603&language=english&go=Search Note this
search doesn't
include things like the sequence of primes.
On Sun, Jul 19, 2020 at 2:28 AM Tomasz Ordowski <tomaszordowski at gmail.com>
wrote:
> Dear SeqFans!
>
> Let a(0) = p and a(n) = 2 a(n-1) + 1. Note that a(n) = (p+1) 2^n - 1.
> Are there primes p such that a(n) is composite for every n > 0 ?
>
> Best regards,
>
> Thomas Ordowski
> _______________________
> https://en.wikipedia.org/wiki/Riesel_number
>
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