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A086661
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Numbers n such that n*4^n-1 is prime.
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14
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1, 2, 3, 5, 8, 14, 23, 63, 107, 132, 428, 530, 1137, 1973, 2000, 7064, 20747, 79574, 113570, 293912, 1993191
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OFFSET
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1,2
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COMMENTS
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2, 3, 5, 23, 107, 1973, 20747 is the subsequence of prime terms.
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REFERENCES
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H. Dubner, Generalized Cullen Numbers, J. Rec. Math, 21 (No. 3, 1989).
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LINKS
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EXAMPLE
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2 is in the sequence because 2*4^2-1=31 is prime.
3 is in the sequence because 3*4^3-1=191 is prime.
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MATHEMATICA
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Do[If[PrimeQ[n*4^n-1], Print[n]], {n, 4000}]
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PROG
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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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EXTENSIONS
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One more term from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 23 2004
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
Prepended first terms 1 and 2 - Pierre CAMI, Jul 21 2014
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STATUS
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approved
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