A270228 Number of matchings in the n X n rook graph K_n X K_n.

1, 7, 370, 270529, 3337807996, 855404716021831, 5352265402523357926168, 940288991338542314571521981185, 5236753179470435264288904589157765055760, 1029720447530443779943631183186535523331685533812231

Offset

1,2

Comments

K_n X K_n is also called the rook graph or lattice graph.

Links

Andrew Howroyd, Table of n, a(n) for n = 1..16

Andrew Howroyd, C# software related to this sequence

Eric Weisstein's World of Mathematics, Independent Edge Set

Eric Weisstein's World of Mathematics, Matching

Eric Weisstein's World of Mathematics, Rook Graph

Wikipedia, Rook's graph, Hosoya index

Crossrefs

Cf. A270227, A270229, A085537 (Wiener index), A002720 (independent vertex sets), A269561, A028420.

Sequence in context: A221353 A222870 A270247 * A082443 A082624 A332137

Adjacent sequences: A270225 A270226 A270227 * A270229 A270230 A270231

Keyword

nonn,changed

Author

Andrew Howroyd, Mar 13 2016

Status

approved