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Search: id:A087648
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| A087648 |
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(1/2)*(Bell(n+2)+Bell(n+1)-Bell(n)). |
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+0
3
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| 1, 3, 9, 31, 120, 514, 2407, 12205, 66491, 386699, 2388096, 15589732, 107165081, 773106715, 5836100685, 45981026703, 377230766908, 3215977070706, 28437411817135, 260380616093533, 2464930698184351
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Sum of last number in all set partitions of n+1. E.g. The set partitions of 3 are {1,1,1}, {1,1,2}, {1,2,1}, {1,2,2}, and {1,2,3}, so a(2) = 1+2+1+2+3 = 9. - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jun 07 2006
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MATHEMATICA
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f[0]=1; f[n_] := Sum[ StirlingS2[n, k]*Binomial[k+2, k ], {k, 1, n}]; Table[ f[n], {n, 0, 20}] - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 31 2007
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CROSSREFS
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Cf. A000110, A035098, A059606.
Main diagonal of A120057, row sums of A120095.
Sequence in context: A110136 A073724 A066571 this_sequence A086616 A040027 A071603
Adjacent sequences: A087645 A087646 A087647 this_sequence A087649 A087650 A087651
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Sep 23 2003
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