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
Harald A. Helfgott and Ira M. Gessel, Tilings of Diamonds and Hexagons with Defects, Electron. J. Combin., 6 (1999) (see Theorem 20).
Sean A. Irvine, Java program (github)
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
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