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Largest number b for which A181780(n) is a Fermat pseudoprime.
6

%I #5 Apr 13 2012 15:03:46

%S 11,13,18,25,23,29,25,37,31,35,29,34,37,55,57,49,47,51,49,49,43,81,59,

%T 88,61,56,89,97,73,81,91,109,69,118,83,25,68,85,81,125,109,95,131,133,

%U 97,137,145,67,94,107,139,142,150,134,165,151,113,119,121,179

%N Largest number b for which A181780(n) is a Fermat pseudoprime.

%C That is, the largest b for which b^(s-1) = 1 (mod s), where s is in A181780.

%H T. D. Noe, <a href="/A211457/b211457.txt">Table of n, a(n) for n = 1..10000</a>

%t t = {}; n = 1; While[Length[t] < 100, n++; If[! PrimeQ[n], s = Select[Range[2, n-2], PowerMod[#, n-1, n] == 1 &]; If[s != {}, AppendTo[t, {n, Length[s], s}]]]]; Last/@Transpose[t][[3]]

%Y Cf. A181780, A211455, A211456, A211458.

%K nonn

%O 1,1

%A _T. D. Noe_, Apr 13 2012