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A145958 Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation. 0
1, 1, 1, 1, 1, 9, 19, 37, 135, 441, 1879, 9853, 53945, 336895, 2463469, 20551403, 200816385, 2276422523, 29317863291, 437152357559, 7466970790985, 147328291419831, 3346732661121193 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

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

EXAMPLE

Maximal 8 X 8 example:

0 1 0 0 0 1 1 0

1 1 0 1 1 0 1 1

1 0 1 0 1 1 0 0

0 1 1 0 0 0 1 0

0 1 0 0 0 1 1 0

0 0 1 1 0 1 0 1

1 1 0 1 1 0 1 1

0 1 1 0 0 0 1 0

CROSSREFS

Sequence in context: A157034 A198590 A297396 * A290245 A039299 A211114

Adjacent sequences: A145955 A145956 A145957 * A145959 A145960 A145961

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 25 2008

STATUS

approved

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Last modified January 26 16:14 EST 2023. Contains 359833 sequences. (Running on oeis4.)