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A020231 Strong pseudoprimes to base 5. 20
781, 1541, 5461, 5611, 7813, 13021, 14981, 15751, 24211, 25351, 29539, 38081, 40501, 44801, 53971, 79381, 100651, 102311, 104721, 112141, 121463, 133141, 141361, 146611, 195313, 211951, 216457, 222301, 251521, 289081, 290629, 298271, 315121 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..715 from R. J. Mathar)

Eric Weisstein's World of Mathematics, Strong Pseudoprime

Index entries for sequences related to pseudoprimes

MATHEMATICA

nmax = 400000; sppQ[n_?EvenQ, _] := False; sppQ[n_?PrimeQ, _] := False; sppQ[n_, b_] := (s = IntegerExponent[n-1, 2]; d = (n-1)/2^s; If[ PowerMod[b, d, n] == 1, Return[True], Do[If[PowerMod[b, d*2^r, n] == n-1, Return[True]], {r, 0, s - 1}]]); A020231 = {}; n = 1; While[n < nmax, n = n+2; If[sppQ[n, 5] == True, Print[n]; AppendTo[A020231, n]]]; A020231 (* Jean-Fran├žois Alcover, Oct 20 2011, after R. J. Mathar *)

CROSSREFS

Cf. A005936, A001262 (base-2 SPP), A020229 (base-3 SPP), A215568 (SPP to bases 2 & 5), A215566 (SPP to bases 3 & 5), A056915 (SPP to bases 2, 3 & 5), A074773 (SPP to bases 2, 3, 5 & 7).

Sequence in context: A250952 A139400 A115467 * A141390 A038477 A236888

Adjacent sequences:  A020228 A020229 A020230 * A020232 A020233 A020234

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified September 19 02:22 EDT 2020. Contains 337175 sequences. (Running on oeis4.)