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A098891
Define the n-omino graph to be the graph whose vertices are each of the n-ominoes, two of which are joined by an edge if one can be obtained from the other by cutting out one of the latter's component squares (thus obtaining an (n-1)-omino for most cases) and gluing it elsewhere. The sequence counts the edges in these graphs.
8
0, 0, 1, 8, 47, 266, 1339, 6544, 29837, 133495, 585002, 2542563, 10959656
OFFSET
1,4
COMMENTS
In some cases the act of removing a component square (temporarily) disconnects the polyomino before the component is reattached elsewhere. - Sean A. Irvine, Apr 13 2020
See A367435 for the case where the cells remaining after detaching the square to be moved must be a connected polyomino. - Pontus von Brömssen, Nov 18 2023
LINKS
Freddy Barrera, Picture for a(5), 2020.
Freddy Barrera, Picture for a(6), 2020.
Sean A. Irvine, Java program (github)
FUNG Cheok Yin, Tetrominoes
FUNG Cheok Yin, Maxima code for n = 4 and n = 5, Apr 13 2020
CROSSREFS
Half the row sums of A367126.
Cf. A367435.
Sequence in context: A296631 A255720 A014524 * A054488 A034349 A296797
KEYWORD
nonn,more
AUTHOR
Bernardo Recamán, Nov 08 2004
EXTENSIONS
a(4) corrected by FUNG Cheok Yin, Feb 11 2020
a(5) corrected and a(6)-a(12) from Sean A. Irvine and Freddy Barrera, Apr 13 2020
a(13) from Pontus von Brömssen, Nov 05 2023
STATUS
approved