A123998: No primes except 3?

[zak seidov]

Great!
It'so easy if you are Max, not Zak!
Thanks, 
Zak

--- "Max A." <maxale at gmail.com> wrote:

> Note that if n = 1 mod 3 then 2n+1 is not prime
> (except n=1);
> and if n = 2 mod 3 then 4n+1 is not prime.
> Therefore, n must be a multiple of 3, except n=1.
> 
> Max
> 
> If n>1 and both 2n+1, 4n+1 are primes
> 
> On 11/2/06, zak seidov <zakseidov at yahoo.com> wrote:
> > Why are there no prime numbers except of 3,
> > in this sequence?
> > Zak
> >
> > A123998
> >
>
={1,3,9,15,18,39,48,69,78,99,105,114,135,153,165,168,183,189,219,249,273,
> >
> >
>
288,300,303,309,330,345,363,405,414,438,468,483,498,504,534,585,618,
> >  639,648,699,714,729,765,804,813,828,879,933};
> > (* %N A123998 Numbers n for which 2n+1 and 4n+1
> are
> > primes. *)
> >
> >
> >
> >
> >
>
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