two further puzzles
Jack Brennen
jb at brennen.net
Tue Nov 29 00:15:14 CET 2005
> Can anyone figure them out?
> %S A112037 2,3,5,11,7,23,13,29,41
> %S A112038 5,7,11,23,29,47,53,59,83
Here's the PARI/GP code I threw together. I get these same sequences,
except that I think the second sequence rightfully begins with 3,
rather than 5.
g=1;forprime(p=2,299,f=factorint(p-1)[,1];z=factorback(f);
r=z/gcd(z,g);g*=r;if(r>1,print(r," ",p)));
Essentially, go through all of the primes p, and for each one, factor p-1
into primes. List the primes in the order of their first appearance in
the p-1 factorizations -- that gives you A112037. For each member r of
A112037, give the smallest prime p which is congruent to 1 (mod r) --
that gives you A112038. (Or you could think of it as the "p" values
which produced new members of A112037.)
Jack
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