A020159 Pseudoprimes to base 31.

6, 10, 15, 30, 49, 65, 66, 133, 185, 451, 481, 561, 637, 931, 946, 1105, 1221, 1729, 1813, 2317, 2405, 2465, 2553, 3310, 4753, 4921, 6241, 6289, 6601, 7107, 7421, 7449, 8177, 8911, 9073, 9131, 10470, 10585, 10963, 11041, 12403, 14191, 16219, 17767, 18721

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Composite numbers n such that 31^(n-1) == 1 (mod n).

Links

• R. J. Mathar and T. D. Noe, Table of n, a(n) for n = 1..1000 (R. J. Mathar 837 terms)
• Index entries for sequences related to pseudoprimes

Crossrefs

Cf. A001567 (pseudoprimes to base 2).

Programs

Mathematica

base = 31; 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 *)