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A145779 Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only either two adjacent vertically or two adjacent horizontally. 0
1, 1, 1, 4, 8, 17, 58, 224, 939, 4970, 30996, 225413, 1970184, 20575972, 252185309, 3690646219, 64088665934, 1323737025941, 32350145726565, 942783467265088, 32507076170340916, 1335377761740727698, 64933573760903971267 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..23.

CROSSREFS

Sequence in context: A335274 A296399 A119471 * A252790 A144178 A075558

Adjacent sequences:  A145776 A145777 A145778 * A145780 A145781 A145782

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 18 2008

STATUS

approved

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Last modified October 26 05:58 EDT 2021. Contains 348257 sequences. (Running on oeis4.)