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A180978
Number of n X n binary matrices with floor(n^2/2) 1's and rows and columns in lexicographically nondecreasing order
0
1, 3, 10, 121, 3680, 326650, 91271990, 74872992399, 208579984612008, 1748923742658486631
(list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Diagonal of A180979
LINKS
Table of n, a(n) for n=1..10.
EXAMPLE
All solutions for 3X3
..0..0..0....0..0..0....0..0..0....0..0..1....0..0..1....0..0..1....0..0..1
..0..1..1....0..0..1....0..1..1....0..1..0....0..0..1....0..1..0....0..1..0
..0..1..1....1..1..1....1..0..1....0..1..1....0..1..1....1..1..0....1..0..1
...
..0..0..1....0..0..1....0..1..1
..0..0..1....0..1..1....1..0..0
..1..1..0....1..0..0....1..0..0
CROSSREFS
Sequence in context: A336210 A244305 A074260 * A241461 A175079 A333430
Adjacent sequences: A180975 A180976 A180977 * A180979 A180980 A180981
KEYWORD
nonn
AUTHOR
R. H. Hardin Sep 30 2010
STATUS
approved

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Last modified September 28 14:04 EDT 2024. Contains 376297 sequences.
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