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A091442
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Table (by antidiagonals) of permutations of two types of objects so that each cycle contains at least one object of each type. Each type of object unlabeled.
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0
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1, 1, 1, 1, 3, 1, 1, 3, 3, 1, 1, 5, 8, 5, 1, 1, 5, 11, 11, 5, 1, 1, 7, 17, 26, 17, 7, 1, 1, 7, 24, 40, 40, 24, 7, 1, 1, 9, 31, 66, 85, 66, 31, 9, 1, 1, 9, 39, 95, 146, 146, 95, 39, 9, 1, 1, 11, 50, 139, 245, 304, 245, 139, 50, 11, 1, 1, 11, 59, 183, 379, 538, 538, 379, 183, 59, 11
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OFFSET
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1,5
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REFERENCES
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F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, pg 114 (2.4.42)
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LINKS
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Table of n, a(n) for n=1..77.
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FORMULA
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G.f.: A(x, y) = Product_{k>=1} (1-x^n)*(1-y^n)/(1-x^n-y^n).
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EXAMPLE
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1 1 1 1 1 ...
1 3 3 5 5 ...
1 3 8 11 17 ...
1 5 11 26 40 ...
1 5 17 40 85 ...
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CROSSREFS
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Sequence in context: A174546 A134444 A176149 * A025834 A035649 A094782
Adjacent sequences: A091439 A091440 A091441 * A091443 A091444 A091445
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KEYWORD
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nonn,tabl
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AUTHOR
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Christian G. Bower, Jan 09 2004
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STATUS
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approved
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