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A001770
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Numbers k such that 5*2^k - 1 is prime.
(Formerly M1087 N0415)
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11
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2, 4, 8, 10, 12, 14, 18, 32, 48, 54, 72, 148, 184, 248, 270, 274, 420, 1340, 1438, 1522, 1638, 1754, 1884, 2014, 2170, 2548, 2622, 2652, 2704, 13510, 21738, 25624, 41934, 51478, 52540, 53230, 172300, 245728, 350028, 1194164
(list;
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listen;
history;
text;
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OFFSET
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1,1
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COMMENTS
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REFERENCES
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N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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MAPLE
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MATHEMATICA
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PROG
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CROSSREFS
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Cf. A002254 (5*2^n+1 is prime), A050522 (primes of the form 5*2^n - 1).
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KEYWORD
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nonn,nice,hard,more
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AUTHOR
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EXTENSIONS
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a(40) from the Wilfrid Keller link by Robert Price, Dec 22 2018
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STATUS
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approved
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