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Search: id:A033713
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| A033713 |
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Number of zeros in numbers 1 to 999..9 (n digits). |
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+0
5
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| 0, 9, 189, 2889, 38889, 488889, 5888889, 68888889, 788888889, 8888888889, 98888888889, 1088888888889, 11888888888889, 128888888888889, 1388888888888889, 14888888888888889, 158888888888888889
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Also the first n places of 1, ..., n-digit numbers in the almost-natural numbers (A007376). - Erich Friedman (erich.friedman(AT)stetson.edu).
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REFERENCES
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M. Kraitchik, Mathematical Recreations. Dover, NY, 2nd ed., 1953, p. 49.
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FORMULA
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a(n) = (1/9)*((n-1)*(10^n)-n*10^(n-1)+1); g.f.: (9*x^2)/((1-x)(1-10x)^2) - Stephen G. Penrice (spenrice(AT)ets.org), Oct 01 2000
Sum 9i*10^(i-1), i=1..n.
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MATHEMATICA
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Table[ Sum[9i*10^(i - 1), {i, 1, n}], {n, 0, 16}]
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CROSSREFS
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Cf. A033714.
Sequence in context: A078101 A133556 A124008 this_sequence A067422 A145240 A113564
Adjacent sequences: A033710 A033711 A033712 this_sequence A033714 A033715 A033716
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KEYWORD
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nonn,base,nice,easy
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AUTHOR
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Olivier Gorin (gorin(AT)roazhon.inra.fr)
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EXTENSIONS
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More terms from Erich Friedman (erich.friedman(AT)stetson.edu).
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