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A078486
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Number of irreducible indecomposable pop-stack permutations of a certain type.
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0
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0, 1, 2, 6, 24, 102, 414, 1598, 5982, 22102, 81442, 300562, 1111638, 4117382, 15259738, 56561346, 209629750, 776850166, 2878660394, 10666717442, 39524757670, 146456879830, 542691221946, 2010931777154, 7451478924278, 27611353095414, 102313463160906
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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REFERENCES
| M. D. Atkinson and T. Stitt, Restricted permutations and the wreath product, Discrete Math., 259 (2002), 19-36.
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FORMULA
| G.f.: (x-7*x^2+19*x^3-21*x^4+10*x^5-6*x^6)/(1-9*x+31*x^2-53*x^3+44*x^4-16*x^5+6*x^6).
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CROSSREFS
| Sequence in context: A150299 A094012 A141253 * A129817 A128652 A152316
Adjacent sequences: A078483 A078484 A078485 * A078487 A078488 A078489
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Jan 04 2003
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