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Pseudoprimes to base 51.
1

%I #16 Oct 20 2016 14:16:58

%S 10,25,50,65,70,91,175,325,451,481,925,1247,1681,1729,1825,2059,2275,

%T 2653,2821,3053,3790,4745,4927,5461,6175,6305,6505,6601,7201,8365,

%U 8911,9031,9475,9730,9850,10585,11041,12025,12209,12403,13366,13427,13747

%N Pseudoprimes to base 51.

%C Composite numbers n such that 51^(n-1) == 1 (mod n).

%H T. D. Noe, <a href="/A020179/b020179.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 = 51; 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[15000],CompositeQ[#]&&PowerMod[51,#-1,#]==1&] (* _Harvey P. Dale_, Oct 20 2016 *)

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

%K nonn

%O 1,1

%A _David W. Wilson_