[seqfan] More rows of triangle in A271100?

David Corneth davidacorneth at gmail.com
Mon May 16 14:05:23 CEST 2016


Hi all,

In search for more Wieferich n-tuples, I'd like to propose another approach
to finding them. The problem can be represented as finding cycles in a
directed graph. The nodes are the primes. The arcs are pairs (p, q) of
primes such that p^(q - 1) == 1 (mod q^2). An n-tuple is found when a cycle
of length n is found in the graph. For example, arcs are (3, 11), (11, 71)
and (71, 3). This gives the cycles of length 3 (3, 11, 71, 3), (11, 71, 31,
11) and (71, 3, 11, 71). Any ideas on this?

Best,
David


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