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A316906
Numbers k such that 2^(k-1) == 1 (mod k) and lpf(k)-1 does not divide k-1.
2
7957, 23377, 30889, 35333, 42799, 49981, 60787, 91001, 129889, 150851, 162193, 164737, 241001, 249841, 253241, 256999, 280601, 318361, 387731, 452051, 481573, 556169, 580337, 617093, 665333, 722201, 838861, 877099, 1016801, 1251949, 1252697, 1325843, 1507963
OFFSET
1,1
COMMENTS
Are there infinitely many such pseudoprimes?
LINKS
EXAMPLE
7957 = 73*109 is pseudoprime and 72 does not divide 7956.
30889 = 17*23*79 is pseudoprime and 16 does not divide 30888.
MATHEMATICA
Select[Range[760000] 2 + 1, PowerMod[2, #-1, #] == 1 && Mod[#-1, FactorInteger[#][[1, 1]] - 1] > 0 &] (* Giovanni Resta, Jul 16 2018 *)
CROSSREFS
Subsequence of A001567.
Cf. A020639 (lpf(n)).
Sequence in context: A023322 A064246 A260959 * A316907 A293623 A316908
KEYWORD
nonn
AUTHOR
Thomas Ordowski, Jul 16 2018
EXTENSIONS
a(8)-a(33) from Giovanni Resta, Jul 16 2018
STATUS
approved