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Search: id:A140425
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A140425 Number of n X n symmetric binary matrices with every 1 adjacent to another 1 horizontally or vertically. +0
1
1, 4, 28, 342, 8170, 388316, 35871274, 6434968504, 2248575047080, 1530856226085764, 2029777404349820818, 5241143888167535563974, 26356732501074298121803368, 258136468277025366420232101764 (list; graph; listen)
OFFSET

1,2
CROSSREFS

Sequence in context: A007152 A113371 A080636 this_sequence A165193 A095288 A155105

Adjacent sequences: A140422 A140423 A140424 this_sequence A140426 A140427 A140428

KEYWORD

nonn

AUTHOR

Ron Hardin (rhhardin(AT)att.net), Jun 18 2008

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Last modified December 10 00:48 EST 2009. Contains 170565 sequences.

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