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A057784
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Number of polypons with n cells.
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4
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1, 2, 2, 4, 4, 10, 13, 29, 47, 100, 181, 383, 738, 1539, 3087, 6419, 13135, 27402, 56779, 118876, 248384, 521850, 1096261, 2310793, 4874305, 10305560
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| A polypon is a polyform made up of 30-30-120 triangles from the [3.12^2] Laves tiling, joined along their edges. Because that tiling contains hexagons formed as a union of six triangles, with the division of the hexagon having less symmetry than the hexagon on its own, some polypons can be divided into their constituent triangles in more than one way, and whether the division is significant affects the values of a(n) when n >= 18 is a multiple of 6. For the present sequence, the division into triangles is considered significant. - Joseph Myers, Oct 02 2011
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REFERENCES
| Computed by Brendan Owen.
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LINKS
| Ed Pegg, Jr., Illustrations of polyforms
Andrew Clarke, Other Polyforms
Eric Weisstein's World of Mathematics, Polypon [From Eric W. Weisstein (eric(AT)weisstein.com), Apr 24 2009]
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CROSSREFS
| Cf. A057785, A151531, A151532, A151533.
Sequence in context: A170831 A133406 A005293 * A081164 A125553 A138317
Adjacent sequences: A057781 A057782 A057783 * A057785 A057786 A057787
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KEYWORD
| nonn,nice,hard
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 04 2000
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EXTENSIONS
| Link updated by William Rex Marshall (w.r.marshall(AT)actrix.co.nz), Dec 16 2009
a(21)-a(26) from Joseph Myers (jsm(AT)polyomino.org.uk), Oct 02 2011
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