A020166 - OEIS

%I #20 Jan 22 2023 11:51:34

%S 39,65,85,91,111,185,221,259,289,469,481,561,629,697,871,1105,1221,

%T 1443,1445,2405,2465,2479,2553,2665,2701,2821,3145,3367,3585,3757,

%U 4033,4187,4681,5291,5461,6031,6097,6601,6931,7449,7585,7613,7957,8177,9073,9919

%N Pseudoprimes to base 38.

%C Composite numbers n such that 38^(n-1) == 1 (mod n). - _Michel Lagneau_, Feb 18 2012

%H T. D. Noe, <a href="/A020166/b020166.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 = 38; 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[10000],CompositeQ[#]&&PowerMod[38,#-1,#]==1&] (* _Harvey P. Dale_, Jan 22 2023 *)

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

%K nonn

%O 1,1

%A _David W. Wilson_