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A145796 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only either four adjacent vertically or four adjacent horizontally. 0
1, 1, 1, 3, 9, 16, 93, 367, 2220, 13167, 126326, 1163166, 15908600, 209043350, 4432902382, 88370483688 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..16.

CROSSREFS

Sequence in context: A197531 A117108 A223188 * A056403 A181349 A240094

Adjacent sequences:  A145793 A145794 A145795 * A145797 A145798 A145799

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 19 2008

STATUS

approved

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Last modified October 20 17:38 EDT 2019. Contains 328268 sequences. (Running on oeis4.)