A139010 Number of n X n symmetric binary matrices containing no more than two 1s in any 3 X 3 sub-block.

1, 2, 5, 10, 46, 298, 1984, 21540, 331078, 6336017, 173488605, 6651795802, 340061007958, 23986915555236, 2342976613039703, 311875652121439248, 56925380854171209808, 14298682300093479646164, 4921580523122987792169589

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