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A007788
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Number of augmented Andre 3-signed permutations: E.g.f. (1-sin(3*x))^(-1/3).
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3
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1, 1, 4, 19, 136, 1201, 13024, 165619, 2425216, 40132801, 740882944, 15091932019, 336257744896, 8134269015601, 212309523595264, 5946914908771219, 177934946000306176, 5663754614516217601
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| 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
| 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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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..200
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FORMULA
| E.g.f.: (1-sin(3*x))^(-1/3).
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MATHEMATICA
| With[{nn=20}, CoefficientList[Series[(1-Sin[3x])^(-1/3), {x, 0, nn}], x] Range[0, nn]!] (* From Harvey P. Dale, Nov 23 2011 *)
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CROSSREFS
| Cf. A007863.
Sequence in context: A127060 A134147 A157303 * A197920 A067577 A203010
Adjacent sequences: A007785 A007786 A007787 * A007789 A007790 A007791
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KEYWORD
| nonn,changed
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AUTHOR
| R. Ehrenborg and M. A. Readdy [ehrenbor(AT)lacim.uqam.ca, readdy(AT)lacim.uqam.ca].
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