A020169 - OEIS

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A020169

Pseudoprimes to base 41.

4, 8, 10, 15, 20, 21, 35, 40, 105, 145, 231, 344, 561, 609, 645, 671, 703, 841, 1065, 1105, 1281, 1387, 1417, 1729, 1885, 1891, 2121, 2465, 2701, 2821, 3045, 3053, 3829, 4033, 4205, 4521, 4870, 5365, 5565, 6161, 6892, 7957, 8295, 8321, 8695, 8905, 8911, 9253

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OFFSET

1,1

COMMENTS

Composite numbers n such that 41^(n-1) == 1 (mod n).

LINKS

R. J. Mathar, Table of n, a(n) for n=1..1003

Index entries for sequences related to pseudoprimes

MATHEMATICA

base = 41; 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 *)

PROG

(Magma) [n: n in [1..3*10^4] | IsOne(Modexp(41, n-1, n)) and not IsPrime(n)]; // Vincenzo Librandi, Mar 15 2019