OFFSET
1,2
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 6, note a(2) is erroneous in this reference, cf. A071092).
LINKS
Ilse Fischer, Moments of inertia associated with the lozenge tilings of a hexagon, 2000.
J. Propp, Updated article
J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), New Perspectives in Algebraic Combinatorics
FORMULA
a(n) = (7*n^4 - n^2) / 6.
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Jun 27 2024
STATUS
approved