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A131539
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Least power of 2 having exactly n consecutive 5's in its decimal representation.
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2
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8, 16, 76, 41, 1162, 973, 6838, 25265, 81782, 456686, 279270, 1727606, 6030753, 23157026
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OFFSET
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1,1
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COMMENTS
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No more terms < 28*10^6.
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LINKS
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Popular Computing (Calabasas, CA), Two Tables, Vol. 1, (No. 9, Dec 1973), page PC9-16.
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EXAMPLE
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a(3)=76 because 2^76(i.e. 75557863725914323419136) is the smallest power of 2 to contain a run of 3 consecutive fives in its decimal form.
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MATHEMATICA
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a = ""; Do[ a = StringJoin[a, "5"]; b = StringJoin[a, "5"]; k = 1; While[ StringPosition[ ToString[2^k], a] == {} || StringPosition[ ToString[2^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]
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CROSSREFS
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KEYWORD
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more,nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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