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A145780 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only either two adjacent vertically or two adjacent horizontally. 0
1, 1, 5, 18, 70, 523, 4956, 70926, 1300201, 37116376, 1354115636, 76887328413, 5596162598050, 631149201335604, 91196507989935319, 20473605176808584691, 5885534752273786907540, 2626715298620574785397735 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..18.

CROSSREFS

Sequence in context: A343490 A302077 A322773 * A183443 A034551 A052926

Adjacent sequences:  A145777 A145778 A145779 * A145781 A145782 A145783

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 18 2008

STATUS

approved

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Last modified December 5 14:32 EST 2021. Contains 349557 sequences. (Running on oeis4.)