A139006 - OEIS

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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: A006797 A144239 A320951 * A338868 A213943 A153701

Adjacent sequences: A139003 A139004 A139005 * A139007 A139008 A139009

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 31 2008

STATUS

approved