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A228076
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Numbers k such that (19^k - 4^k)/15 is prime.
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0
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2, 7, 11, 31, 47, 139, 263, 769, 20551, 21491, 112247
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OFFSET
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1,1
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COMMENTS
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All terms are prime.
a(12) > 2*10^5.
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LINKS
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MATHEMATICA
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Select[Prime[Range[1, 100000]], PrimeQ[(19^# - 4^#)/15]&]
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PROG
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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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