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Search: id:A131539
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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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+0
1
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OFFSET
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1,1
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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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Sequence in context: A022444 A089828 A082982 this_sequence A117868 A062508 A083086
Adjacent sequences: A131536 A131537 A131538 this_sequence A131540 A131541 A131542
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KEYWORD
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more,nonn,base
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AUTHOR
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Shyam Sunder Gupta (guptass(AT)rediffmail.com), Aug 26 2007
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