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Search: id:A111897
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| A111897 |
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Number of numbers m <= n such that 7 equals the second digit after decimal point of square root of n in decimal representation. |
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+0
12
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| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
(list; graph; listen)
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OFFSET
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1,20
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COMMENT
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For n>1: if A111862(n)=7 then a(n)=a(n-1)+1 else a(n)=a(n-1).
a(n)/n --> 1/10.
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REFERENCES
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G. Polya and G. Szego, Problems and Theorems in Analysis I (Springer 1924, reprinted 1972), Part Two, Chap. 4, Sect. 4, Problem 178.
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EXAMPLE
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a(10) = 0, a(100) = 7, a(1000) = 100, a(10000) = 1000.
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CROSSREFS
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Cf. A111890, A111891, A111892, A111893, A111894, A111895, A111896, A111898, A111899, A111857.
Sequence in context: A108622 A112348 A127321 this_sequence A135665 A135662 A111853
Adjacent sequences: A111894 A111895 A111896 this_sequence A111898 A111899 A111900
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KEYWORD
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nonn,base
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 20 2005
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