[seqfan] Re: 2225

[Tomasz Ordowski]

Dear SeqFans,

(*) I agree with David, who used the smallest Riesel number 509203.

(**) Daniel Suteu, on the other hand, noticed that adding the ones at the
end of the binary number 509203 leads to the original Riesel problem.

Thomas

śr., 29 maj 2019 o 17:17 David Radcliffe <dradcliffe at gmail.com> napisał(a):

> The number 539373 has this property, but it is probably not the smallest.
> We can check that every number of the form 2^n - 509203 is divisible by one
> of the primes {3, 5, 7, 13, 17, 241}.
> Therefore, 2^n - 2^20 + 539373 is composite for all n >= 20.
>
> > On Wed, May 29, 2019, 07:33 Tomasz Ordowski <tomaszordowski at gmail.com>
> > > wrote:
> > >
> > > > What is the smallest odd number that,
> > > > preceded by any number of 1's in base 2, gives only composite
> numbers?
> >
> >
>
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