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A145794 Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only either four adjacent vertically or four adjacent horizontally. 0
1, 1, 1, 1, 1, 2, 1, 3, 2, 5, 6, 12, 20, 34, 68, 154, 265, 709, 1281, 3847, 8603, 25073, 71217, 206107, 695670, 2185029, 7989257, 27851353, 111404338, 424685942 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..30.

CROSSREFS

Sequence in context: A102517 A062951 A263150 * A176741 A266138 A014000

Adjacent sequences:  A145791 A145792 A145793 * A145795 A145796 A145797

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 19 2008

STATUS

approved

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Last modified August 23 01:10 EDT 2019. Contains 326211 sequences. (Running on oeis4.)