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Search: id:A005046
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| A005046 |
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Number of partitions of n-set into even blocks.
(Formerly M3640)
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+0
14
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| 1, 1, 4, 31, 379, 6556, 150349, 4373461, 156297964, 6698486371, 337789490599, 19738202807236, 1319703681935929, 99896787342523081, 8484301665702298804, 802221679220975886631, 83877585692383961052499
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Louis Comtet, Analyse Combinatoire Tome II, pages 61-62.
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 225, 3rd line of table.
CRC Standard Mathematical Tables and Formulae, 30th ed. 1996, p. 42.
L. B. W. Jolley, Summation of Series. 2nd ed., Dover, NY, 1961, p. 150.
L. Lovasz, Combinatorial Problems and Exercises, North-Holland, 1993, pp. 15.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..50
S. R. Finch, Moments of sums
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FORMULA
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E.g.f.: exp ( cosh x - 1 ) (or exp(cos(x)-1) ).
Recurrence: a(n) = Sum_{k=1..n} binomial(2*n-1, 2*k-1)*a(n-k). - Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 10 2003
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MATHEMATICA
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NestList[ Factor[ D[ #1, {x, 2} ] ]&, Exp[ Cosh[ x ]-1 ], n ] /. (x->0)
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CROSSREFS
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A000110, A003724.
Sequence in context: A128709 A138860 A145087 this_sequence A141827 A143077 A005841
Adjacent sequences: A005043 A005044 A005045 this_sequence A005047 A005048 A005049
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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