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 A020159 Pseudoprimes to base 31. 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 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) 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 *) CROSSREFS Cf. A001567 (pseudoprimes to base 2). Sequence in context: A315288 A238047 A272398 * A048017 A332392 A048078 Adjacent sequences:  A020156 A020157 A020158 * A020160 A020161 A020162 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 24 19:51 EDT 2020. Contains 337321 sequences. (Running on oeis4.)