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A032360
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Numbers k such that 21*2^k+1 is prime.
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3
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1, 4, 5, 7, 9, 12, 16, 17, 41, 124, 128, 129, 187, 209, 276, 313, 397, 899, 1532, 1613, 1969, 2245, 2733, 4585, 4644, 6712, 6981, 13344, 17524, 27124, 29769, 47337, 55828, 91008, 94801, 164901, 179457, 191337, 200568, 220992, 686632, 856865, 1022168, 1240067
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Select[Range[1000], PrimeQ[21*2^#+1] &] (* Amiram Eldar, Dec 12 2018 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013
a(47) from http://www.prothsearch.com/riesel1.html by Robert Price, Dec 12 2018
Terms moved from Data to b-file, and new term added to b-file, by Jeppe Stig Nielsen, Aug 29 2020
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STATUS
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approved
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