[seqfan] Re: Almost A111076

[Tomasz Ordowski]

Emmanuel, thank you for the simple proof.

Note that, for n > 1, a(prime(n)) = A053760(n).

Thomas

śr., 13 lis 2019 o 10:27 Emmanuel Vantieghem <emmanuelvantieghem at gmail.com>
napisał(a):

> >
> > The conjecture is true.
> > If  a(n)  was not prime for some  n, it was the product of two numbers b,
> > c  both coprime to  n
> > and strictly smaller than  a(n).  If  m = carmichael's lambda(n), we then
> > have : b^(m/2) == c^(m/2) ==1 mod n)  and hence
> > a(n)^(m/2) == 1 mod n,  Impossible.
> >
>
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