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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. 1
0, 0, 1, 8, 47, 266, 1339, 6544, 29837, 133495, 585002, 2542563 (list; graph; refs; listen; history; text; internal format)
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

LINKS

Table of n, a(n) for n=1..12.

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

Sequence in context: A296631 A255720 A014524 * A054488 A034349 A296797

Adjacent sequences:  A098888 A098889 A098890 * A098892 A098893 A098894

KEYWORD

nonn,more

AUTHOR

Bernardo Recamán (ignotus(AT)hotmail.com), 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

STATUS

approved

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Last modified April 23 05:42 EDT 2021. Contains 343199 sequences. (Running on oeis4.)