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A020146 Pseudoprimes to base 18. 1
25, 49, 65, 85, 133, 221, 323, 325, 343, 425, 451, 637, 931, 1105, 1225, 1369, 1387, 1649, 1729, 1921, 2149, 2465, 2701, 2821, 2825, 2977, 3325, 4165, 4577, 4753, 5525, 5725, 5833, 5941, 6305, 6517, 6601, 7345, 8911, 9061, 10349, 10585, 10961, 11221 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Composite numbers n such that 18^(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 = 18; 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 *)

CROSSREFS

Cf. A001567 (pseudoprimes to base 2).

Sequence in context: A278931 A181782 A322121 * A020244 A020196 A020294

Adjacent sequences:  A020143 A020144 A020145 * A020147 A020148 A020149

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified March 19 11:10 EDT 2019. Contains 321329 sequences. (Running on oeis4.)