

A071091


Number of tilings by lozenges of hexagon with sides 2n, 2n+3, 2n, 2n+3, 2n, 2n+3 and middle triangle in each edge removed.


0




OFFSET

1,2


REFERENCES

J. Propp, Enumeration of matchings: problems and progress, pp. 255291 in L. J. Billera et al., eds, New Perspectives in Algebraic Combinatorics, Cambridge, 1999 (see Problem 2).


LINKS

Table of n, a(n) for n=1..5.
M. Ciucu et al., Enumeration of lozenge tilings of hexagons with a central triangular hole, arXiv:math/9912053 [math.CO], 1999.
J. Propp, Update on Enumeration of Matchings, 2009.
J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), New Perspectives in Algebraic Combinatorics


CROSSREFS

Sequence in context: A234440 A254635 A189655 * A209826 A107582 A213869
Adjacent sequences: A071088 A071089 A071090 * A071092 A071093 A071094


KEYWORD

nonn,changed


AUTHOR

N. J. A. Sloane, May 28 2002


STATUS

approved



