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Search: id:A102287
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| A102287 |
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Total number of even blocks in all partitions of n-set. |
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+0
3
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| 0, 1, 3, 13, 55, 256, 1274, 6791, 38553, 232171, 1477355, 9898780, 69621864, 512585529, 3940556611, 31560327945, 262805569159, 2271094695388, 20333574916690, 188322882941471, 1801737999086129, 17783472151154007
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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E.g.f: (cosh(x)-1)*exp(exp(x)-1).
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EXAMPLE
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a(3)=3 because in the 5 (=A000110(3)) partitions 123, (12)/3, (13)/2, 1/(23), and 1/2/3 of {1,2,3} we have 3 blocks of even size (shown between parentheses).
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MAPLE
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G:=(cosh(x)-1)*exp(exp(x)-1): Gser:=series(G, x=0, 28): seq(n!*coeff(Gser, x^n), n=1..25); (Deutsch)
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CROSSREFS
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Cf. A005493, A000296.
Adjacent sequences: A102284 A102285 A102286 this_sequence A102288 A102289 A102290
Sequence in context: A093834 A033887 A117376 this_sequence A006225 A100588 A081952
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Feb 19 2005
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 22 2005
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