A020168 Pseudoprimes to base 40.

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

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