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A069788 Number of tilings by lozenges of hexagon with sides n, n+1, n, n+1, n, n+1 and central triangle removed. 0
2, 54, 4320, 2500000, 5252187500, 68336412238080, 3507134014317846528, 1039468958911770833166336, 1271288794044247678785011427072, 8629570422218326431392139107794299444, 248662702551142788293946930136251315440514048, 38763625610496798571986566181715696354290667009540096 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
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).
LINKS
J. Propp, Updated article
J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), New Perspectives in Algebraic Combinatorics
CROSSREFS
Sequence in context: A338514 A123686 A122418 * A283678 A306266 A117681
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 28 2002
EXTENSIONS
Propp gives 12 terms.
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003
STATUS
approved

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Last modified September 29 23:48 EDT 2023. Contains 365781 sequences. (Running on oeis4.)