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Search: id:A136364
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| A136364 |
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a(n) = Sum_{ composite k, 1 <= k <= 10^n} (Number of divisors d of k with 1 < d < k). |
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+0
2
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| 8, 283, 5070, 73669, 966751, 11970035, 142725365, 1657511569, 18877697635
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = A057494(n) - 2*10^n + 1 [From Max Alekseyev (maxale(AT)gmail.com), May 10 2009]
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EXAMPLE
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a(1)=8 because there are 8 distinct divisors of composite numbers k through 10^1; these are for 4(1); 6(2); 8(2); 9(1); 10(2); and 1+2+2+1+2=8.
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CROSSREFS
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Cf. A136363.
Adjacent sequences: A136361 A136362 A136363 this_sequence A136365 A136366 A136367
Sequence in context: A129424 A045479 A079929 this_sequence A089670 A060355 A060859
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KEYWORD
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easy,more,nonn
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AUTHOR
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Enoch Haga (Enokh(AT)comcast.net), Dec 26 2007, Dec 29 2007
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Jan 12 2008
Three more terms from Max Alekseyev (maxale(AT)gmail.com), May 10 2009
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