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A230537
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Numbers n such that 3^7*2^n - 1 is prime.
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3
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1, 2, 6, 13, 22, 29, 30, 33, 36, 50, 61, 118, 180, 226, 405, 433, 522, 789, 929, 960, 1026, 1030, 1118, 1266, 1521, 1718, 2536, 3029, 3366, 4253, 9157, 10165, 23641, 29877, 30648, 47265, 56097, 90501, 101981, 103021, 108370, 117909, 157237, 169156, 174168
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OFFSET
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1,2
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COMMENTS
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Riesel Primes with k = 3^7 = 2187.
Checked up to n = 1000000.
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LINKS
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EXAMPLE
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2187*2^1-1=4373 is a prime number.
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MATHEMATICA
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b=3^7; i=0; Table[While[i++; cp=b*2^i-1; !PrimeQ[cp]]; i, {j, 1, 30}]
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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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Lei Zhou, Nov 08 2013, added a Mathematica program for small elements.
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STATUS
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approved
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