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A140419
Number of n X n symmetric binary matrices with every element adjacent horizontally (and vertically) to some 0.
0
1, 5, 8, 21, 175, 1984, 27783, 566775, 18973984, 977497059, 72692403175, 7984795118976, 1348773682858701, 345874419612107295, 131649476800621708800, 74856171576736831201899
OFFSET
2,2
CROSSREFS
Sequence in context: A036381 A363224 A277369 * A292851 A138023 A120037
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 17 2008
STATUS
approved