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Composite numbers n such that k! == 1 (mod n) for some k > 2.
2

%I #12 Feb 05 2018 03:00:04

%S 119,121,221,299,391,527,901,961,1387,1643,1829,2047,2627,3569,5083,

%T 9641,9869,10379,11449,16337,16517,18349,22577,23267,23999,25199,

%U 27931,28471,31877,32989,33431,37127,40319,47029,48827,50933,52777,55277

%N Composite numbers n such that k! == 1 (mod n) for some k > 2.

%C Conjecture: If c is composite then n! == 1 (mod c) for at most one n >= 2. - David Wilson, Oct 06 2009

%H D. Wilson, <a href="/A049048/b049048.txt">Table of n, a(n) for n = 1..1000</a>

%K nonn

%O 1,1

%A _David W. Wilson_