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A199191
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Numbers k such that 3^(2k-3) + 3^(k-1) + 1 is prime.
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2
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2, 3, 4, 5, 6, 10, 11, 41, 83, 160, 178, 526, 881, 2578, 3772, 11873
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OFFSET
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1,1
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COMMENTS
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Numbers k such that A198410(k) is prime.
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LINKS
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MATHEMATICA
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Select[Range[250], PrimeQ[((3^(#-1) + 1)^3 -1)/3^#]&]
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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