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A095967
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Numbers n such that r3(k) * 2^n + 1 is prime, where r3() = A002277 and k is the number of decimal digits of 2^n.
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0
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1, 2, 6, 9, 20, 46, 58, 64, 69, 110, 158, 178, 186, 268, 424, 624, 641, 1236, 1593, 2264, 2870, 5797, 7518, 7688, 9300
(list;
graph;
refs;
listen;
history;
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internal format)
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OFFSET
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1,2
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COMMENTS
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a(1) through a(25) have been proved to be prime with WinPFGW. a(25) has 5600 digits. No more terms up to 12800.
Results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019
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LINKS
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EXAMPLE
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a(4)=9 because 333 * 2^9 + 1 = 170497, a prime.
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CROSSREFS
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KEYWORD
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more,nonn,base
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AUTHOR
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STATUS
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approved
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