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Search: id:A056047
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| A056047 |
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Number of 4-antichain covers of a labeled n-set. |
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+0
2
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| 0, 0, 0, 0, 25, 1895, 70370, 1868650, 41062035, 802349205, 14514339340, 249104207000, 4120588431245, 66392465654515, 1049608974433110, 16365222591176550
(list; graph; listen)
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OFFSET
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0,5
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REFERENCES
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V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)
V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.
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LINKS
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K. S. Brown, Dedekind's problem
Eric Weisstein's World of Mathematics, Antichain covers"
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FORMULA
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a(n)=(1/4!)*(15^n - 12*11^n + 24*9^n + 4*8^n - 18*7^n + 6*6^n - 36*5^n + 36*4^n + 11*3^n - 22*2^n + 6).
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CROSSREFS
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Cf. A051112.
Sequence in context: A125826 A033981 A023113 this_sequence A051112 A061843 A135057
Adjacent sequences: A056044 A056045 A056046 this_sequence A056048 A056049 A056050
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic, Goran Kilibarda (vladeta(AT)Eunet.yu), Jul 25 2000
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