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A054887
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Layer counting sequence for hyperbolic tessellation by cuspidal triangles of angles (Pi/3,Pi/5,Pi/7).
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0
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1, 3, 6, 11, 20, 36, 64, 113, 200, 354, 626, 1107, 1958, 3464, 6128, 10839, 19172, 33913, 59988, 106111, 187696, 332009, 587280, 1038820, 1837534, 3250353, 5749442, 10169998, 17989372, 31820803, 56286764, 99563792, 176115092
(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.: (1+x)*(x^3-1)*(x^5-1)*(x^7-1)/(x^16-2*x^15+x^12+x^10-x^4-x^6+2*x-1).
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CROSSREFS
| Sequence in context: A055417 A018918 A077855 * A019302 A119861 A018075
Adjacent sequences: A054884 A054885 A054886 * A054888 A054889 A054890
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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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