A020231 Strong pseudoprimes to base 5.

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

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-François 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: A139400 A115467 A338877 * A141390 A038477 A236888

Adjacent sequences: A020228 A020229 A020230 * A020232 A020233 A020234

Keyword

nonn

Author

David W. Wilson

Status

approved