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A191551 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 diagonally or antidiagonally neighboring 1 1
2, 8, 33, 297, 4032, 91392, 3461143, 214272233, 22066261672, 3754762272000, 1054824912314030, 490291568481195135, 376674319103188012304, 478415094920126210097672, 1004588343161199901448153154 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..26

EXAMPLE

Some solutions for n=4

..1..1..1..1....0..0..0..1....1..0..1..0....1..1..0..1....0..0..0..0

..1..0..0..0....0..1..0..0....0..0..1..1....1..1..0..0....0..1..0..0

..1..0..0..0....0..0..1..0....1..1..0..0....0..0..0..1....0..0..0..0

..1..0..0..1....1..0..0..0....0..1..0..0....1..0..1..0....0..0..0..1

CROSSREFS

Sequence in context: A236382 A269890 A005040 * A263627 A172448 A268601

Adjacent sequences:  A191548 A191549 A191550 * A191552 A191553 A191554

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 05 2011

STATUS

approved

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Last modified December 6 22:42 EST 2021. Contains 349567 sequences. (Running on oeis4.)