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Pseudoprimes to base 62.
1

%I #21 Jan 23 2022 13:51:03

%S 9,21,45,63,91,105,183,231,305,361,427,549,561,671,679,703,793,861,

%T 1105,1261,1281,1541,1729,2121,2465,2501,2745,2871,3367,3439,3843,

%U 3845,4141,4187,4577,5185,5307,5551,5565,5901,5917,6161,6405,6533,6601,6697,6849

%N Pseudoprimes to base 62.

%C Composite numbers k such that 62^(k-1) == 1 (mod k). - _Michel Lagneau_, Feb 18 2012

%H T. D. Noe, <a href="/A020190/b020190.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 = 62; 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[7000],CompositeQ[#]&&PowerMod[62,#-1,#]==1&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jul 20 2019 *)

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

%K nonn

%O 1,1

%A _David W. Wilson_