A243221 Number of quarter-square matchings of the n X n grid graph.

1, 1, 4, 44, 2593, 407620, 333518324, 696849783788, 7561681603209033, 204785162442300693673, 28874426647917459828127044, 10023323177854055068860282476760, 18172145684566998309243670369029131178, 80387219406473992671391703779030095453926416

Offset: 0

Author

Alois P. Heinz, Jun 01 2014

Keywords

• nonn

Comments

Number of ways floor(n^2/4) dominoes can be placed on an n X n chessboard. a(n) is the central term in the n-th row of A242861.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..14

Crossrefs

Cf. A002620, A242861.

Formula

a(n) = A242861(n,floor(n^2/4)) = A242861(n,A002620(n)).