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Search: id:A136363
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| A136363 |
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a(n) = Sum_{ composite k, 1 <= k <= 10^n} (Sum of divisors d of k with 1 < d < k). |
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+0
2
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| 23, 3150, 321582, 32241015, 3224590836, 322466618438, 32246696794797, 3224670272194238, 322467032612360629, 32246703337400266401, 3224670334173560419030, 322467033423857340138979
(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) = A072692(n) - 10^n*(10^n+3)/2 + 1 [From Max Alekseyev (maxale(AT)gmail.com), May 10 2009]
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EXAMPLE
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a(1)=23 because the divisors through 10^1 are as follows: 4 (2); 6 (2,3); 8 (2,4); 9 (3); 10 (2,5). The sum is 2+2+3+2+4+3+2+5=23.
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CROSSREFS
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Cf. A136364.
Sequence in context: A088385 A030461 A152521 this_sequence A134798 A103443 A059000
Adjacent sequences: A136360 A136361 A136362 this_sequence A136364 A136365 A136366
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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
Extended by Max Alekseyev (maxale(AT)gmail.com), May 10 2009
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