A180981 - OEIS

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A180981

T(n,k)=number of nXk binary matrices with floor((n*k)/2) 1's and rows in lexicographically nonincreasing order and columns in lexicographically strictly increasing order

1, 1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 0, 1, 2, 1, 0, 0, 1, 2, 3, 1, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 1, 3, 5, 4, 1, 0, 0, 0, 0, 1, 5, 6, 4, 1, 0, 0, 0, 0, 1, 3, 8, 8, 5, 1, 0, 0, 0, 0, 0, 1, 6, 12, 10, 5, 1, 0, 0, 0, 0, 0, 1, 4, 12, 18, 13, 6, 1, 0, 0, 0, 0, 0, 0, 1, 8, 20, 24, 15, 6, 1, 0, 0, 0, 0, 0, 0, 1, 4, 18, 32, 33

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,9

COMMENTS

Table starts

.1.1..0..0...0...0...0...0...0...0..0..0.0.0

.1.1..1..0...0...0...0...0...0...0..0..0.0.0

.1.2..1..1...0...0...0...0...0...0..0..0.0.0

.1.2..2..1...1...0...0...0...0...0..0..0.0.0

.1.3..3..3...1...1...0...0...0...0..0..0.0.0

.1.3..5..5...3...1...1...0...0...0..0..0.0.0

.1.4..6..8...6...4...1...1...0...0..0..0.0.0

.1.4..8.12..12...8...4...1...1...0..0..0.0.0

.1.5.10.18..20..18..10...5...1...1..0..0.0.0

.1.5.13.24..32..32..24..13...5...1..1..0.0.0

.1.6.15.33..49..58..49..33..15...6..1..1.0.0

.1.6.18.43..73..94..94..73..43..18..6..1.1.0

.1.7.21.55.102.151.169.151.102..55.21..7.1.1

.1.7.25.69.141.227.289.289.227.141.69.25.7.1

LINKS

R. H. Hardin, Table of n, a(n) for n=1..365

EXAMPLE

All solutions for 6X3

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

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

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

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

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

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

CROSSREFS

Sequence in context: A257181 A164116 A164118 * A284317 A281243 A284314

Adjacent sequences: A180978 A180979 A180980 * A180982 A180983 A180984

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Sep 30 2010

STATUS

approved