## Re: number of selfridges?

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• ... I made a big mistake with negation in my tests, so that tests 2-5 are not necessary. However, test 1. stands without any known counterexample found by me
Message 1 of 46 , Dec 2, 2011
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--- In primenumbers@yahoogroups.com, "paulunderwooduk" <paulunderwood@...> wrote:
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>
>
> --- In primenumbers@yahoogroups.com, "paulunderwooduk" <paulunderwood@> wrote:
> >
> >
> >
> > --- In primenumbers@yahoogroups.com, "paulunderwooduk" <paulunderwood@> wrote:
> > >
> > > Sorry about the SN ratio....
> > >
> > > I now have the following composite tests for which I would like to know their selfridge values:
> > >
> > > 1. for kronecker(5,n)==-1:
> > > Mod(Mod(1,n)*(l^2-2),l^2-3*l+1)^(n+1)+9==0
> > >
> > > 3. for n==9 (mod 10):
> > > Mod(Mod(1,n)*(l^2-2),l^2-3*l+1)^((n+1)/2)+3*l-3==0
> > >
> > > 4. for n==9 (mod 10) or n==11 (mod 20):
> > > Mod(Mod(1,n)*(l^2-2),l^2-3*l+1)^((n+1)/2)+3*l-3==0
> > >
> > > (gcd(n,30)==1)
> > >
> >
> > 5. kronecker(5,n)==1 and n!=1 (mod 60)
> > Mod(Mod(1,n)*(l^2-2),l^2-3*l+1)^((n+1)/2)+3*l-3==0
> >
> > 1. and 5. have been checked against Richard Pinch's Carmichael numbers list for n less than 10^16,
> >
>
> 5. fails for some numbers in Pinch's 2-PSP list (n<10^12) which are 41 mod(60) ... so that leaves 11,21,31,51 mod(60)?
>

I made a big mistake with negation in my tests, so that tests 2-5 are not necessary. However, test 1. stands without any known counterexample found by me yet. I can re-write it slightly differently

1b. for kronecker(5,n)==-1:
Mod(Mod(1,n)*3*(l-1),l^2-3*l+1)^(n+1)+9==0

Paul
• ... Combining fails with the composite counterexample n=256999 and x=32768, However, I have tested the 1+1+1+2 conjecture up to n
Message 46 of 46 , Apr 14, 2012
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--- In primenumbers@yahoogroups.com, "paulunderwooduk" <paulunderwood@...> wrote:
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>
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> --- In primenumbers@yahoogroups.com, "paulunderwooduk" <paulunderwood@> wrote:
> >
> > Hi,
> >
> > I have added a Fermat test to make a 1+1+1+2 selfridge test:
> >
> > For N>5, with gcd(6,N)==1, find an integer x:
> > gcd(x^3-x,N)==1
> > kronecker(x^2-4,N)==-1
> >
> > and check:
> > (x+2)^((N-1)/2)==kronecker(x+2,N) (mod N) (Euler)
> > (x-2)^((N-1)/2)==kronecker(x-2,N) (mod N) (Euler)
> > x^(N-1)==1 (mod N) (Fermat)
> > L^(N+1) == 1 (mod N, L^2-x*L+1) (Lucas)
> >
>
> Note: I should say gcd(30,N)==1 because gcd(x^3-x,N)==1 and kronecker(x^2-4,n)==-1.
>
>
> Now consider combining the 2 Euler tests with the Lucas test:
>
> (L*D)^((n+1)/2)==D (mod N, L^2-x*L+1) (D=x^2-4.)
>
> with the restriction kronecker(x+2,N)==-1.
>
> These together with the Fermat test makes for a 1+2-selfridge test.
>
> Can you find a counterexample?
>
> So far the near-refutation from Pinch's carmichael list is:
> N,x,gcd(x^2-1)
> ------------------
> 1909001 884658 1909001
>
> Paul
>

Combining fails with the composite counterexample n=256999 and x=32768, However, I have tested the 1+1+1+2 conjecture up to n<10^7,

Paul -- restoring symmetry
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