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Search: id:A131543
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| A131543 |
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Least power of 2 having exactly n consecutive 9's in its decimal representation. |
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+0
1
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| 12, 33, 50, 421, 422, 2187, 15554, 42483, 42485, 42486
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(3)=50 because 2^50(i.e. 1125899906842624) is the smallest power of 2 to contain a run of 3 consecutive nines in its decimal form.
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MATHEMATICA
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a = ""; Do[ a = StringJoin[a, "9"]; b = StringJoin[a, "9"]; 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: A045660 A050690 A079561 this_sequence A063296 A051624 A039338
Adjacent sequences: A131540 A131541 A131542 this_sequence A131544 A131545 A131546
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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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