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Search: id:A014668
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| A014668 |
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a(1)=1, a(n)=sum(k=1, n-1, sum( d|k, a(d))). |
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+0
3
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| 1, 1, 3, 7, 16, 33, 71, 143, 295, 594, 1206, 2413, 4871, 9743, 19559, 39138, 78428, 156857, 314047, 628095, 1256809, 2513693, 5028594, 10057189, 20116979, 40233975, 80472823, 160945945, 321901713, 643803427, 1287627061, 2575254123
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Contribution from Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 30 2009: (Start)
Equals eigensequence of triangle A010766 and starting (1, 3, 7, 16, 33,...) =
row sums of triangle A163313 (End)
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FORMULA
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a(n) is asymptotic ot c*2^n where c=0.59960731361450033896934...
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PROGRAM
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(PARI) // an=vector(100); a(n)=if(n<0, 0, an[n]); // an[1]=1; for(n=2, 100, an[n]=sum(k=1, n-1, sumdiv(k, d, a(d))))
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CROSSREFS
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A010766, A163313 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 30 2009]
Sequence in context: A161810 A084631 A002936 this_sequence A054455 A026734 A026767
Adjacent sequences: A014665 A014666 A014667 this_sequence A014669 A014670 A014671
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 24 2003
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