

A020168


Pseudoprimes to base 40.


1



39, 91, 121, 123, 289, 451, 533, 561, 703, 793, 1541, 1561, 1599, 1729, 1921, 2821, 2899, 3097, 3367, 3751, 3829, 4961, 5461, 5729, 6031, 6601, 7111, 7201, 7381, 8911, 9073, 9881, 10897, 11011, 11041, 11121, 11521, 12403, 12801, 13073, 13333, 13981
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OFFSET

1,1


COMMENTS

Composite numbers n such that 40^(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

base = 40; pp40 = {}; n = 1; While[Length[pp40] < 100, n++; If[!PrimeQ[n] && PowerMod[base, n  1, n] == 1, AppendTo[pp40, n]]]; pp40 (* T. D. Noe, Feb 21 2012 *)
searchMax = 10000; Complement[Select[Range[searchMax], PowerMod[40, #  1, #] == 1 &], Prime[Range[PrimePi[searchMax]]]] (* Alonso del Arte, Feb 20 2020 *)


CROSSREFS

Cf. A001567 (pseudoprimes to base 2).
Sequence in context: A044177 A044558 A242181 * A063318 A039422 A043245
Adjacent sequences: A020165 A020166 A020167 * A020169 A020170 A020171


KEYWORD

nonn


AUTHOR

David W. Wilson


STATUS

approved



