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A139008
Number of x X n symmetric binary matrices containing no more than three 1s in any 2 X 2 sub-block.
1
1, 2, 7, 49, 648, 16475, 801489, 74700792, 13333992705, 4558747755857, 2985167883475040, 3743977846899435969, 8993695705522239110137, 41379357418095833391759776, 364644672948881035681654421967
OFFSET
0,2
LINKS
R. H. Hardin, May 31 2008, Table of n, a(n) for n = 0..23
CROSSREFS
Sequence in context: A293043 A377826 A186860 * A058721 A363862 A340027
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 31 2008
STATUS
approved