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

0,3

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

Formula

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

Crossrefs

Cf. A002620, A242861.

Sequence in context: A296729 A157193 A224784 * A238816 A327196 A024254

Adjacent sequences: A243218 A243219 A243220 * A243222 A243223 A243224

Keyword

nonn

Author

Alois P. Heinz, Jun 01 2014

Status

approved