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A145790
Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only either four adjacent vertically or four adjacent horizontally.
0
1, 1, 1, 9, 11, 36, 65, 515, 2420, 18065, 172108, 1981958, 24609296, 431265080, 7420809238, 183434050306, 4983211868325, 173511007323269, 7989094384834315, 376330135051842303, 28830157229045747299, 1923394214566012353119
OFFSET
1,4
CROSSREFS
Sequence in context: A130730 A153697 A129399 * A345109 A143465 A201999
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 19 2008
STATUS
approved