[seqfan] Question about Dickson ordering (see links).
Michel Marcus
michel.marcus183 at gmail.com
Sat Apr 23 14:00:49 CEST 2022
Hello seqfans
Here are 2 links: https://www.jstor.org/stable/2969383 and
https://www.jstor.org/stable/2968678.
I wrote a PARI program to give the ordering of cords.
isp2(n) = my(m); ispower(n,,&m) && (m==2);
row(n) = {
if (n % 2,
my(p = (n-1)/2);
my(c = if (!isp2(n-1), 2, 3)); \\ here it is to take care of 17 and 257
(as he wrote)
my(k=1, v=vector(p));
for (i=1, p,
v[i] = k;
k *= c;
if (k>p, k = n-k);
);
v;
);
}
It is not clear to me if this is supposed to be used for any n ? or for
odd n ?? or for n prime ???
So to test I only do forprime(n=3, 37, print(n, " ", row(n)))
The output for n=13 and 19 match what we see in 1st link; and for n=37 what
we see in 2nd link.
But the method does not seem to work for n=31.
But the tripling method does not work for n=17 and n=257.
Do you see how it should work for these values?
Thanks.
MM
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