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A275575
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Numbers k such that (3^k + 1)/(3 - (-1)^k) is a prime.
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1
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2, 3, 4, 5, 7, 13, 16, 23, 32, 43, 64, 281, 359, 487, 577, 1579, 1663, 1741, 3191, 9209, 11257, 12743, 13093, 17027, 26633, 104243, 134227, 152287, 700897, 1205459
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OFFSET
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1,1
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LINKS
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MAPLE
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MATHEMATICA
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Select[Range[0, 10^3], PrimeQ[(3^# + 1)/(3 - (-1)^#)] &]
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PROG
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(PARI) isok(n) = isprime( (3^n + 1)/(3 - (-1)^n)); \\ Michel Marcus, Dec 26 2016
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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