A180982 - OEIS

A180982

Number of n X n binary matrices with floor(n^2/2) 1's and rows in lexicographically nondecreasing order and columns in strictly increasing order

1, 2, 6, 71, 2403, 238535, 73506103, 64732546521, 189964969385932, 1647943050926969975

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OFFSET

1,2

COMMENTS

Diagonal of A180983

LINKS

EXAMPLE

All solutions for 3X3

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

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

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

CROSSREFS

KEYWORD

nonn

AUTHOR

STATUS

approved