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Pseudoprimes to base 43.
2

%I #16 Aug 17 2017 11:00:47

%S 6,14,21,25,33,42,77,91,105,165,185,231,325,385,425,481,525,561,777,

%T 825,861,925,973,1045,1105,1221,1541,1729,1785,1807,1825,1925,2071,

%U 2425,2465,2553,2821,2849,3145,3281,3439,3781,3885,4033,4417,4825,5005,5565,6105

%N Pseudoprimes to base 43.

%C Composite numbers n such that 43^(n-1) == 1 (mod n).

%H R. J. Mathar, <a href="/A020171/b020171.txt">Table of n, a(n) for n=1..1234</a>

%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>

%t base = 43; t = {}; n = 1; While[Length[t] < 100, n++; If[! PrimeQ[n] && PowerMod[base, n-1, n] == 1, AppendTo[t, n]]]; t (* _T. D. Noe_, Feb 21 2012 *)

%t Select[Range[7000],!PrimeQ[#]&&PowerMod[43,#-1,#]==1&] (* _Harvey P. Dale_, Aug 17 2017 *)

%Y Cf. A001567 (pseudoprimes to base 2).

%K nonn

%O 1,1

%A _David W. Wilson_