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Pseudoprimes to base 90.
1

%I #18 Jun 13 2018 09:15:12

%S 91,623,703,793,1001,1157,1729,2047,2413,2821,3091,3367,4033,4699,

%T 6281,6601,8099,8321,8401,8911,11521,11557,12403,13021,13333,13981,

%U 14701,14981,15841,17701,19307,19951,20017,20263,24641,24661,25571,29341,31021

%N Pseudoprimes to base 90.

%C Composite numbers n such that 90^(n-1) == 1 (mod n). - _Michel Lagneau_, Feb 18 2012

%H T. D. Noe, <a href="/A020218/b020218.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 = 90; 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_