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A180980 T(n,k)=number of nXk binary matrices with floor((n*k)/2) 1's and rows in lexicographically nondecreasing order and columns in lexicographically nonincreasing order 1
1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 3, 3, 3, 1, 1, 3, 5, 5, 3, 1, 1, 4, 6, 8, 6, 4, 1, 1, 4, 8, 12, 12, 8, 4, 1, 1, 5, 10, 18, 20, 18, 10, 5, 1, 1, 5, 13, 24, 32, 32, 24, 13, 5, 1, 1, 6, 15, 33, 49, 58, 49, 33, 15, 6, 1, 1, 6, 18, 43, 73, 94, 94, 73, 43, 18, 6, 1, 1, 7, 21, 55, 102, 151, 169, 151, 102 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Table starts

.1.1..1..1...1...1...1....1....1....1....1.....1.....1.....1.....1......1

.1.2..2..3...3...4...4....5....5....6....6.....7.....7.....8.....8......9

.1.2..3..5...6...8..10...13...15...18...21....25....28....32....36.....41

.1.3..5..8..12..18..24...33...43...55...69....86...104...126...150....177

.1.3..6.12..20..32..49...73..102..141..190...252...325...414...521....649

.1.4..8.18..32..58..94..151..227..338..480...676...920..1242..1636...2137

.1.4.10.24..49..94.169..289..468..734.1117..1656..2385..3370..4672...6375

.1.5.13.33..73.151.289..526..910.1514.2430..3788..5744..8512.12346..17575

.1.5.15.43.102.227.468..910.1667.2934.4968..8150.12954.20094.30441..45207

.1.6.18.55.141.338.734.1514.2934.5448.9686.16660.27718.44916.70922.109583

LINKS

R. H. Hardin, Table of n, a(n) for n=1..363

EXAMPLE

All solutions for 3X4

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

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

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

CROSSREFS

Sequence in context: A103441 A081206 A156044 * A275298 A048570 A090806

Adjacent sequences:  A180977 A180978 A180979 * A180981 A180982 A180983

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Sep 30 2010

STATUS

approved

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Last modified November 21 06:00 EST 2019. Contains 329350 sequences. (Running on oeis4.)