A020160 - OEIS

A020160

Pseudoprimes to base 32.

25, 33, 93, 165, 205, 217, 325, 341, 385, 425, 465, 561, 645, 697, 793, 825, 1023, 1025, 1045, 1057, 1065, 1105, 1353, 1387, 1525, 1705, 1729, 1905, 2047, 2317, 2325, 2465, 2665, 2701, 2761, 2821, 3053, 3157, 3277, 3565, 3813, 4033, 4123, 4141, 4369, 4371

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OFFSET

1,1

COMMENTS

Composite numbers n such that 32^(n-1) == 1 (mod n). - Michel Lagneau, Feb 18 2012

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

Index entries for sequences related to pseudoprimes

MATHEMATICA

pseudos32 = {}; n = 1; While[Length[pseudos32] < 100, n++; If[!PrimeQ[n] && PowerMod[32, n - 1, n] == 1, AppendTo[pseudos32, n]]]; pseudos32 (* T. D. Noe, Feb 21 2012 *)

max = 5000; Complement[Select[Range[max], PowerMod[32, # - 1, #] == 1 &], Prime[Range[PrimePi[max]]]] (* Alonso del Arte, Jun 12 2018 *)

Select[Range[5000], CompositeQ[#]&&PowerMod[32, #-1, #]==1&] (* Harvey P. Dale, Sep 27 2024 *)

PROG

(Magma) [n: n in [3..10000 by 2] | IsOne(Modexp(32, n-1, n)) and not IsPrime(n)]; // Vincenzo Librandi, Jun 13 2018

CROSSREFS

Cf. A001567 (pseudoprimes to base 2).

Sequence in context: A129074 A188443 A068411 * A075452 A231572 A020258

Adjacent sequences: A020157 A020158 A020159 * A020161 A020162 A020163

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved