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A124017 Numbers n for which 2n-1, 4n-1, 8n-1, 16n-1 and 32n-1 are primes. 7
45, 90, 26820, 26925, 30705, 31710, 33375, 63420, 63570, 71805, 83865, 93075, 103185, 127140, 134025, 148050, 170460, 202635, 211035, 223305, 269505, 297225, 303660, 329175, 335625, 362505, 387975, 405270, 405405, 406425, 409755, 463335 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
Select[15*Range[40000], And @@ PrimeQ /@ ({2, 4, 8, 16, 32}*# - 1) &] (* Ray Chandler, Nov 22 2006 *)
Select[15*Range[31000], AllTrue[#*2^Range[5]-1, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Aug 05 2019 *)
CROSSREFS
Sequence in context: A115827 A070002 A101794 * A121925 A044183 A044564
KEYWORD
nonn
AUTHOR
Artur Jasinski, Nov 04 2006
STATUS
approved

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Last modified May 19 14:45 EDT 2024. Contains 372698 sequences. (Running on oeis4.)