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A139010 Number of n X n symmetric binary matrices containing no more than two 1s in any 3 X 3 sub-block. 0
1, 2, 5, 10, 46, 298, 1984, 21540, 331078, 6336017, 173488605, 6651795802, 340061007958, 23986915555236, 2342976613039703, 311875652121439248, 56925380854171209808, 14298682300093479646164, 4921580523122987792169589 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..18.

CROSSREFS

Sequence in context: A018451 A301520 A330967 * A018472 A082593 A124664

Adjacent sequences:  A139007 A139008 A139009 * A139011 A139012 A139013

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 31 2008

STATUS

approved

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Last modified March 29 02:19 EDT 2020. Contains 333104 sequences. (Running on oeis4.)