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A131546
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Least power of 3 having exactly n consecutive 7's in its decimal representation.
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1
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3, 11, 112, 184, 721, 3520, 6643, 12793, 67448, 208380, 364578, 1123485, 9549790
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OFFSET
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1,1
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COMMENTS
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No more terms < 2*10^7.
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LINKS
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Table of n, a(n) for n=1..13.
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EXAMPLE
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a(3)=112 because 3^112(i.e. 273892744995340833777347939263771534786080723599733441) is the smallest power of 3 to contain a run of 3 consecutive sevens in its decimal form.
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MATHEMATICA
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a = ""; Do[ a = StringJoin[a, "7"]; b = StringJoin[a, "7"]; k = 1; While[ StringPosition[ ToString[3^k], a] == {} || StringPosition[ ToString[3^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]
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CROSSREFS
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Sequence in context: A105413 A183381 A136985 * A068693 A036930 A198085
Adjacent sequences: A131543 A131544 A131545 * A131547 A131548 A131549
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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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EXTENSIONS
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a(11)-a(13) from Lars Blomberg, Feb 02 2013
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STATUS
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approved
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