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A054889
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Layer counting sequence for hyperbolic tessellation by regular pentagons of angle 2*Pi/5.
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1, 5, 20, 70, 245, 860, 3015, 10570, 37060, 129935, 455560, 1597225, 5599980, 19633910, 68837825, 241350100, 846189875, 2966799290, 10401800220, 36469419475, 448300820765, 1571773187140, 5510743762630
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The layer sequence is the sequence of the cardinalities of the layers accumulating around a (finite-sided) polygon of the tessellation under successive side-reflections; see the illustration accompanying A054888.
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FORMULA
| G.f.: (x^4+2*x^3+4*x^2+2*x+1)/(x^4-3*x^3-x^2-3*x+1).
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CROSSREFS
| Sequence in context: A000343 A005324 A154638 * A056384 A036683 A054444
Adjacent sequences: A054886 A054887 A054888 * A054890 A054891 A054892
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KEYWORD
| nonn
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AUTHOR
| Paolo Dominici (pl.dm(AT)libero.it), May 23 2000
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