login
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
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin Jun 13 2011
STATUS
approved