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A180976 Number of n X n binary matrices with floor(n^2/2) 1's and rows and columns in lexicographically strictly increasing order 0
1, 1, 5, 50, 1823, 189359, 61746973, 57086318681, 174484293356777, 1558231919489703557 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Diagonal of A180977

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

All solutions for 3X3

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

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

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

CROSSREFS

Sequence in context: A247951 A082100 A299353 * A305844 A303132 A070995

Adjacent sequences:  A180973 A180974 A180975 * A180977 A180978 A180979

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 30 2010

STATUS

approved

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Last modified August 24 18:52 EDT 2019. Contains 326295 sequences. (Running on oeis4.)