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A146431 Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in a 101-111-101 pattern in any orientation. 0
1, 1, 3, 1, 3, 1, 9, 3, 31, 9, 301, 19, 1647, 53, 11872, 531, 136892, 5709, 3186390, 48307, 72335276, 490649, 1826857009, 11283333, 67665636761, 359196547, 4149252095689, 11541091447, 314296409403995, 440660012263 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
EXAMPLE
Maximal 8 X 8 example
.1.0.1.0.0.1.0.1
.1.1.1.0.0.1.1.1
.1.0.1.0.0.1.0.1
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0
.1.0.1.0.0.1.0.1
.1.1.1.0.0.1.1.1
.1.0.1.0.0.1.0.1
CROSSREFS
Sequence in context: A068503 A073575 A363533 * A212183 A115716 A079412
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)