A020208 Pseudoprimes to base 80.

9, 27, 49, 81, 169, 237, 301, 333, 481, 553, 561, 637, 711, 891, 1221, 1377, 1557, 1729, 1813, 1891, 2107, 2133, 2553, 2821, 2871, 2997, 3321, 3397, 3439, 3537, 3577, 3871, 3913, 5461, 6253, 6399, 6401, 6533, 6601, 6697, 7107, 7189, 7613, 7821, 8261, 8281

Offset

1,1

Comments

Composite numbers n such that 80^(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 = 80; 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 *)
Select[Range[10000], !PrimeQ [#]&&PowerMod[80, #-1, #]==1&] (* Harvey P. Dale, Nov 20 2013 *)

Crossrefs

Cf. A001567 (pseudoprimes to base 2).

Sequence in context: A062231 A133636 A369564 * A020306 A330680 A069068

Adjacent sequences: A020205 A020206 A020207 * A020209 A020210 A020211

Keyword

nonn

Author

David W. Wilson

Status

approved