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Search: id:A007788
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| A007788 |
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Number of augmented Andre 3-signed permutations: expansion of (1-sin 3x)^(-1/3). |
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+0
2
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| 1, 1, 4, 19, 136, 1201, 13024, 165619, 2425216, 40132801, 740882944, 15091932019, 336257744896, 8134269015601, 212309523595264, 5946914908771219, 177934946000306176, 5663754614516217601
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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It appears that all members are of the form 3k+1. - Ralf Stephan (ralf(AT)ark.in-berlin.de), Nov 12 2007
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REFERENCES
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R. Ehrenborg and M. A. Readdy, The r-cubical lattice and a generalization of the cd-index, European J. Combin. 17 (1996), no. 8, 709-725.
R. Ehrenborg and M. A. Readdy, Sheffer posets and r-signed permutations. Ann. Sci. Math. Quebec, 19 (1995), no. 2, 173-196.
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FORMULA
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E.g.f.: (1-sin 3x)^(-1/3).
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CROSSREFS
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Cf. A007863.
Sequence in context: A135742 A127060 A134147 this_sequence A067577 A126147 A007411
Adjacent sequences: A007785 A007786 A007787 this_sequence A007789 A007790 A007791
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KEYWORD
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nonn
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AUTHOR
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R. Ehrenborg and M. A. Readdy [ ehrenbor(AT)lacim.uqam.ca, readdy(AT)lacim.uqam.ca ].
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