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Pseudoprimes to base 30.
1

%I #18 Jun 13 2018 09:16:41

%S 49,91,133,217,247,341,403,469,493,589,637,703,871,899,901,931,1273,

%T 1519,1537,1729,2059,2077,2821,3097,3277,3283,3367,3577,4081,4097,

%U 4123,5729,6031,6061,6097,6409,6601,6817,7657,8023,8029,8401,8911,9881,11041,11713

%N Pseudoprimes to base 30.

%C Composite numbers n such that 30^(n-1) == 1 (mod n). - _Michel Lagneau_, Feb 18 2012

%H T. D. Noe, <a href="/A020158/b020158.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 = 30; 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_