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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, 1, 23, 1608, 371500, 328956227, 1126022690953, 14806761014366079, 744494518032208898560, 142687918961909575461700797, 103997384424546478979311463191760, 287748628673335369235353717267441839979, 3018422667417995172483450578913829739500058615 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 27 11:26 EDT 2021. Contains 348276 sequences. (Running on oeis4.)