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A065868
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Initial n digits in decimal portion of golden ratio phi (or tau) = (1 + sqrt 5)/2 form a prime number.
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0
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OFFSET
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1,1
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COMMENTS
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887 certified prime with Primo.
Note: the upper bound of 10^6 in this program has not actually been reached, so the next term may occur at any value >8867. - Ryan Propper, Aug 12 2005
Search limit is 200000. - Serge Batalov, Jun 21 2017
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LINKS
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Table of n, a(n) for n=1..9.
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MATHEMATICA
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phi = First@ RealDigits[N[GoldenRatio - 1, 10^6 + 1]]; Do[k = FromDigits[Take[phi, n]]; If[PrimeQ[k], Print[n]], {n, 1, 10^6}] (* Ryan Propper, Aug 12 2005, edited by Michael De Vlieger, Jun 21 2017 *)
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CROSSREFS
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Cf. A047658, A057563, A001622.
Sequence in context: A211891 A060599 A319774 * A144017 A032419 A225163
Adjacent sequences: A065865 A065866 A065867 * A065869 A065870 A065871
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KEYWORD
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base,nonn
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AUTHOR
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Jason Earls, Dec 07 2001
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EXTENSIONS
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a(4)-a(6) from Ryan Propper, Aug 12 2005
a(7)-a(9) from Serge Batalov, Jun 21 2017
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STATUS
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approved
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