# [seqfan] Re: New sequence

Charles Greathouse charles.greathouse at case.edu
Wed Apr 5 23:10:00 CEST 2017

```I think it's interesting (and it seems not to be in the OEIS). Modulo
initial terms I have

(PARI) is(n)=if(n%2,return(0)); forprime(p=2,n/2, if(isprime(n-p) &&
(isprime(n+p) || isprime(2*n-p)), return(0))); 1

Charles Greathouse
Case Western Reserve University

On Wed, Apr 5, 2017 at 4:56 PM, Claudio Meller <claudiomeller at gmail.com>
wrote:

> * Sorry almost is wrong, is *at least
>
> 2017-04-05 17:48 GMT-03:00 Claudio Meller <claudiomeller at gmail.com>:
>
> > Because almost one E+p(i) is prime
> > For
> > 10 10+3
> > 14  14+3
> > 16  16+3
> > 18  18+5
> > For
> > 28 = 5+23 = 11+17 and 28+5, 28+23, 28+11 and 28+17 are composite
> >
> > 2017-04-05 17:14 GMT-03:00 Hans Havermann <gladhobo at bell.net>:
> >
> >> >> So :  E = p1 + p2
> >> >> The question is, which even number plus p1 or p2 is not a prime
> number?
> >> >
> >> > Claudio, how are you deciding E = p1 + p2 = p3 + p4 = ... ?
> >>
> >> "I consider all pn (p1, p2, p3, etc)"
> >>
> >> So the question is, which even number plus p1 or p2 or p3 or p4 or ...
> is
> >> not a prime number?
> >>
> >> 10 = 3 +  7 = 5 +  5;   10 + p3 or 10 + p4 is not prime.
> >> 14 = 3 + 11 = 7 +  7;   14 + p2 or 14 + p3 or 14 + p4 is not prime.
> >> 16 = 3 + 13 = 5 + 11;   16 + p3 or 16 + p4 is not prime.
> >> 18 = 5 + 13 = 7 + 11;   18 + p3 is not prime.
> >> ...
> >>
> >> But you do not include 10, 14, 16, 18 in your sequence. Why not?
> >>
> >> --
> >> Seqfan Mailing list - http://list.seqfan.eu/
> >>
> >
> >
> >
> > --
> > Claudio Meller
> > http://grageasdefarmacia.blogspot.com
> > http://todoanagramas.blogspot.com/
> > http://simplementenumeros.blogspot.com/
> >
>
>
>
> --
> Claudio Meller
> http://grageasdefarmacia.blogspot.com
> http://todoanagramas.blogspot.com/
> http://simplementenumeros.blogspot.com/
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>

```