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A064119
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Numbers k such that the first k digits of the Golden Ratio form a prime.
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3
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OFFSET
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1,1
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LINKS
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Eric Weisstein's World of Mathematics, Phi-Prime
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EXAMPLE
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a(1)=7 because the 7-digit number 1618033 is prime.
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MATHEMATICA
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Do[If[PrimeQ[ FromDigits[RealDigits[N[GoldenRatio, n + 10], 10, n][[1]]]], Print[n]], {n, 1, 3000}]
With[{gr=RealDigits[GoldenRatio, 10, 100000][[1]]}, Select[Range[ 100000], PrimeQ[ FromDigits[Take[gr, #]]]&]] (* Harvey P. Dale, Jul 24 2016 *)
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CROSSREFS
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KEYWORD
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base,hard,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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