%I #13 Aug 03 2014 14:01:11
%S 4,9,26,27,28,39,45,52,65,91,117,153,286,351,364,561,585,703,946,1036,
%T 1105,1405,1441,1541,1636,1729,2209,2465,2529,2821,2863,2871,3097,
%U 3277,3367,3406,3481,3653,3861,4005,4564,4777,5317,5833,6031,6364,6433,6601
%N Pseudoprimes to base 53.
%C Composite numbers n such that 53^(n-1) == 1 (mod n).
%H R. J. Mathar, <a href="/A020181/b020181.txt">Table of n, a(n) for n=1..1072</a>
%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%t base = 53; 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_