# [seqfan] Re: both p -/+ 2 is prime power

Neil Sloane njasloane at gmail.com
Sat Oct 17 14:10:39 CEST 2015

```With Robert GH.'s extension, that's a sequence that could be added to the
OEIS,
if someone would do it

Best regards
Neil

Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
Email: njasloane at gmail.com

On Sat, Oct 17, 2015 at 8:01 AM, W. Edwin Clark <wclark at mail.usf.edu> wrote:

> On Sat, Oct 17, 2015 at 4:39 AM, Robert Gerbicz <robert.gerbicz at gmail.com>
> wrote:
>
> > 2015-10-17 10:12 GMT+02:00 W. Edwin Clark <wclark at mail.usf.edu>:
> >
> > > If p = 7 then p+2 = 9 is not prime.
> > >
> >
> > Wrong, he needs prime power, not prime.
> >
>
>
>
>
> > The next two terms:  450283905890997361,36472996377170786401
> > and it is likely that there is no more terms: if p>3 then p-2 or p+2 is
> > divisible by 3, but as that is a prime power it should be in the form of
> > 3^k. So we need: 3^k+2 is prime and 3^k+4 is prime power, or 3^k-2 is
> prime
> > and 3^k-4 is prime power.
> >
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> >
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> >
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```