[seqfan] Re: 2225

[David Radcliffe]

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?
>
>