A330658 Number of ways to place zero or more dominoes on an n X n grid with an equal number of horizontal and vertical dominoes.

1, 1, 1, 23, 1608, 371500, 328956227, 1126022690953, 14806761014366079, 744494518032208898560, 142687918961909575461700797, 103997384424546478979311463191760, 287748628673335369235353717267441839979, 3018422667417995172483450578913829739500058615

Offset

0,4

Links

Table of n, a(n) for n=0..13.

Example

a(1) = a(2) = 1 because the only possibility is placing no dominoes at all.
a(3) = 23 because there is 1 way to place no dominoes, 20 ways to place one horizontal domino and one vertical domino, and 2 ways to place two horizontal and two vertical dominoes.

Crossrefs

Cf. A028420, A332714.

Sequence in context: A248703 A264903 A003281 * A034243 A183480 A002439

Adjacent sequences: A330655 A330656 A330657 * A330659 A330660 A330661

Keyword

nonn

Author

Andrew Howroyd, Mar 01 2020

Status

approved