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Search: id:A131542
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| A131542 |
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Least power of 2 having exactly n consecutive 8's in its decimal representation. |
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+0
1
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| 3, 19, 39, 180, 316, 971, 6836, 25263, 103825, 279274
(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)=39 because 2^39(i.e. 549755813888) is the smallest power of 2 to contain a run of 3 consecutive eights in its decimal form.
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MATHEMATICA
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a = ""; Do[ a = StringJoin[a, "8"]; b = StringJoin[a, "8"]; 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: A117674 A114704 A167053 this_sequence A042371 A141644 A141170
Adjacent sequences: A131539 A131540 A131541 this_sequence A131543 A131544 A131545
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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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