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A156983
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Primes of the form 2^k + 21.
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2
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23, 29, 37, 53, 149, 277, 2069, 32789, 65557, 524309, 17592186044437, 281474976710677, 2251799813685269, 4503599627370517, 2305843009213693973, 11692013098647223345629478661730264157247460343829
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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23 = 2^1 + 21 is in the sequence; 29 = 2^3 + 21 is in the sequence.
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MATHEMATICA
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Delete[Union[Table[If[PrimeQ[2^n + 21], 2^n + 21, 0], {n, 1, 500}]], 1]
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PROG
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(Magma) [ a: n in [1..200] | IsPrime(a) where a is 2^n+21 ]; // Vincenzo Librandi, Nov 27 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Edwin Dyke (ed.dyke(AT)btinternet.com), Feb 20 2009
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EXTENSIONS
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STATUS
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approved
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