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Search: id:A112288
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| A112288 |
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Numerator 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, 2, 11, 47, 4999, 4589867, 1802849, 80995354865, 10388318700333839827, 129530631982136545940863, 460116344514106299899953231, 1272711183040784735474188752842879054737
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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4 consecutive values are primes: 2, 11, 47, 4999. - Jonathan Vos Post (jvospost2(AT)yahoo.com), Sep 08 2005
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EXAMPLE
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a(4) = 47, the numerator 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->numer(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[Numerator[f[n]], {n, 15}] (*Chandler*)
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CROSSREFS
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Cf. A112289.
Adjacent sequences: A112285 A112286 A112287 this_sequence A112289 A112290 A112291
Sequence in context: A089682 A050929 A019005 this_sequence A003442 A054894 A139475
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KEYWORD
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nonn,frac
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), 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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