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Search: id:A112289
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| A112289 |
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Denominator of sum{k=1 to n} 1/s(n,k), where s(n,k) is an unsigned Stirling number of the first kind. |
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+0
2
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| 1, 1, 6, 33, 4200, 4192200, 1705200, 77892963984, 10086416728304192640, 126556188275836361347200, 451535899566923284351392000, 1253032399528279799996000622278320876800
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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a(4) = 33, the denominator of 1/6 + 1/11 + 1/6 + 1 = 47/33.
The first few fractions are: 1, 2, 11/6, 47/33, 4999/4200.
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MAPLE
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with(combinat): a:=n->denom(sum(1/abs(stirling1(n, k)), k=1..n)): seq(a(n), n=1..14); (Deutsch)
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MATHEMATICA
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f[n_] := Sum[1/Abs[StirlingS1[n, k]], {k, n}]; Table[Denominator[f[n]], {n, 15}] (*Chandler*)
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CROSSREFS
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Cf. A112288.
Sequence in context: A118094 A121376 A046707 this_sequence A011798 A044464 A113528
Adjacent sequences: A112286 A112287 A112288 this_sequence A112290 A112291 A112292
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KEYWORD
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nonn,frac
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AUTHOR
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Leroy Quet Sep 01 2005
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EXTENSIONS
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Extended by Emeric Deutsch (deutsch(AT)duke.poly.edu) and Ray Chandler (rayjchandler(AT)sbcglobal.net), Sep 02 2005
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