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A191742 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 E or S neighboring 1 1
2, 6, 34, 354, 6640, 226090, 13978062, 1567580958, 318961138670, 117759554854782, 78883071103925368, 95874600035087067128, 211425486715722284229326, 845949075122781758953188444, 6141355289964517541296446302562 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..36

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Sequence in context: A168362 A274711 A076863 * A181082 A118186 A317080

Adjacent sequences: A191739 A191740 A191741 * A191743 A191744 A191745

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 13 2011

STATUS

approved

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Last modified January 30 02:32 EST 2023. Contains 359939 sequences. (Running on oeis4.)