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Search: id:A093431
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| A093431 |
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a(n)=sum_{k=1..n}(LCM(n,n-1,...,n-k+2,n-k+1)/LCM(1,2,...,k)). |
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+0
11
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| 1, 3, 7, 13, 31, 38, 113, 165, 265, 420, 1607, 1004, 3979, 6893, 4205, 8665, 40903, 49558, 315477, 162320, 79179, 269877, 1647123, 937552, 1810091, 8445653, 7791355, 3978237, 33071543, 19578860, 283536169, 327438713, 117635955
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Comment from Jeremy Gardiner, Dec 28 2008: The following sequences all appear to have the same parity: A003071, A029886, A061297, A092524, A093431, A102393, A104258, A122248, A128975.
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MAPLE
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a:=n->add(lcm(seq(i, i=n-k+1..n))/lcm(seq(j, j=1..k)), k=1..n): seq(a(n), n=1..40); (Deutsch)
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CROSSREFS
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Cf. A093430, A093432, A093433.
Row sums of A093430.
Sequence in context: A100750 A105435 A117708 this_sequence A083520 A162869 A079018
Adjacent sequences: A093428 A093429 A093430 this_sequence A093432 A093433 A093434
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 31 2004
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EXTENSIONS
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Corrected and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 30 2006
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