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Search: id:A069788
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| A069788 |
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Number of tilings by lozenges of hexagon with sides n, n+1, n, n+1, n, n+1 and central triangle removed. |
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+0
1
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| 2, 54, 4320, 2500000, 5252187500, 68336412238080, 3507134014317846528, 1039468958911770833166336, 1271288794044247678785011427072, 8629570422218326431392139107794299444, 248662702551142788293946930136251315440514048, 38763625610496798571986566181715696354290667009540096
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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J. Propp, Enumeration of matchings: problems and progress, pp. 255-291 in L. J. Billera et al., eds, New Perspectives in Algebraic Combinatorics, Cambridge, 1999 (see Problem 1).
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LINKS
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J. Propp, Updated article
J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), New Perspectives in Algebraic Combinatorics
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CROSSREFS
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Sequence in context: A071798 A123686 A122418 this_sequence A117681 A089180 A034013
Adjacent sequences: A069785 A069786 A069787 this_sequence A069789 A069790 A069791
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KEYWORD
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nonn,easy
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AUTHOR
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njas, May 28 2002
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EXTENSIONS
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Propp gives 12 terms.
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003
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