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A139006
Number of n X n symmetric binary matrices containing no more than one 1 in any 2 X 2 sub-block.
1
1, 2, 3, 9, 28, 137, 811, 6884, 75303, 1133287, 22573092, 608722751, 21933950111, 1064082678978, 69200610896639, 6047740350081131, 709281636920027844, 111719166691840119209, 23622672695690329752039
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OFFSET
0,2
LINKS
R. H. Hardin, May 31 2008,
Table of n, a(n) for n = 0..28
CROSSREFS
Sequence in context:
A144239
A320951
A381339
*
A338868
A213943
A153701
Adjacent sequences:
A139003
A139004
A139005
*
A139007
A139008
A139009
KEYWORD
nonn
AUTHOR
R. H. Hardin
, May 31 2008
STATUS
approved
