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A128000
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Numbers n such that (28^n - 1)/27 is prime.
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2
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OFFSET
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1,1
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COMMENTS
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No other terms less than 100000. - Robert Price, May 01 2012
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LINKS
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MATHEMATICA
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Select[Prime[Range[100]], PrimeQ[(28^#-1)/27]&]
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PROG
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CROSSREFS
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KEYWORD
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hard,more,nonn
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AUTHOR
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EXTENSIONS
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1423 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(6)=115877 corresponds to a probable prime discovered by Paul Bourdelais, Dec 08 2017
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STATUS
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approved
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