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 A020229 Strong pseudoprimes to base 3. 17
 121, 703, 1891, 3281, 8401, 8911, 10585, 12403, 16531, 18721, 19345, 23521, 31621, 44287, 47197, 55969, 63139, 74593, 79003, 82513, 87913, 88573, 97567, 105163, 111361, 112141, 148417, 152551, 182527, 188191, 211411, 218791, 221761, 226801 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..24767 (first 752 terms from R. J. Mathar) Joerg Arndt, Matters Computational (The Fxtbook), section 39.10, pp. 786-792 Eric Weisstein's World of Mathematics, Strong Pseudoprime MATHEMATICA 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}]]); A020229 = {}; lst = {}; k = 3; While[k < 500000, If[sppQ[k, 3], Print[k]; AppendTo[lst, k]]; k += 2]; lst (* Jean-François Alcover, Oct 20 2011, after R. J. Mathar *) PROG (PARI) is_A020229(n, b=3)={ bittest(n, 0) || return; ispseudoprime(n) && return; my(d=(n-1)>>valuation(n-1, 2)); Mod(b, n)^d==1 || until(n-1<=d*=2, Mod(b, n)^d+1 || return(1))} \\ M. F. Hasler, Jul 19 2012 CROSSREFS Cf. A001262, A072276, A056915, A074773, A005935. Sequence in context: A014749 A262051 A048950 * A141350 A235408 A190877 Adjacent sequences:  A020226 A020227 A020228 * A020230 A020231 A020232 KEYWORD nonn AUTHOR STATUS approved

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Last modified July 21 19:25 EDT 2019. Contains 325199 sequences. (Running on oeis4.)