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A192840 Number of n X n symmetric 0..1 arrays with each element equal to at least two horizontal or vertical neighbors, containing at least one 1 and with new values 0..1 introduced in lower triangular row major order 1
0, 0, 0, 4, 23, 183, 2051, 34480, 852316, 31436447, 1719054682, 139749375351, 16887682211104, 3032513808121100, 809442991768500675, 321179427812462958356, 189437827654558885755437 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
EXAMPLE
Some solutions for 6X6
..0..0..0..0..1..1....0..0..0..0..1..1....0..0..0..0..0..0....0..0..0..0..1..1
..0..0..0..0..1..1....0..0..0..0..1..1....0..0..0..0..0..0....0..1..1..0..1..1
..0..0..0..0..0..0....0..0..0..0..1..1....0..0..1..1..1..1....0..1..1..0..0..0
..0..0..0..1..1..0....0..0..0..1..1..1....0..0..1..1..1..1....0..0..0..1..1..0
..1..1..0..1..1..0....1..1..1..1..0..0....0..0..1..1..0..0....1..1..0..1..1..0
..1..1..0..0..0..0....1..1..1..1..0..0....0..0..1..1..0..0....1..1..0..0..0..0
CROSSREFS
Sequence in context: A106174 A056814 A058863 * A302189 A292971 A317967
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 11 2011
STATUS
approved

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Last modified May 20 08:57 EDT 2024. Contains 372710 sequences. (Running on oeis4.)