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A020156 Pseudoprimes to base 28. 1

%I

%S 9,27,45,87,145,261,361,529,561,703,783,785,1105,1305,1413,1431,1885,

%T 2041,2413,2465,2871,3201,3277,4553,4699,5149,5181,5365,7065,8149,

%U 8321,8401,9841,10027,10585,12673,13333,13345,13357,13833,14383,14769,14981

%N Pseudoprimes to base 28.

%C Composite numbers n such that 28^(n-1) == 1 (mod n). - _Michel Lagneau_, Feb 18 2012

%H T. D. Noe, <a href="/A020156/b020156.txt">Table of n, a(n) for n = 1..1000</a>

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

%t base = 28; 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 *)

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

%K nonn

%O 1,1

%A _David W. Wilson_

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Last modified October 18 15:21 EDT 2019. Contains 328162 sequences. (Running on oeis4.)