A201375 T(n,k)=Number of nXk 0..1 arrays with rows and columns lexicographically nondecreasing read forwards, and nonincreasing read backwards

2, 2, 2, 2, 3, 2, 2, 4, 4, 2, 2, 5, 8, 5, 2, 2, 6, 14, 14, 6, 2, 2, 7, 22, 36, 22, 7, 2, 2, 8, 32, 80, 80, 32, 8, 2, 2, 9, 44, 157, 268, 157, 44, 9, 2, 2, 10, 58, 280, 786, 786, 280, 58, 10, 2, 2, 11, 74, 464, 2016, 3739, 2016, 464, 74, 11, 2, 2, 12, 92, 726, 4608, 15574, 15574, 4608

Offset

1,1

Comments

Table starts

.2..2..2....2.....2......2........2.........2...........2............2

.2..3..4....5.....6......7........8.........9..........10...........11

.2..4..8...14....22.....32.......44........58..........74...........92

.2..5.14...36....80....157......280.......464.........726.........1085

.2..6.22...80...268....786.....2016......4608........9582........18446

.2..7.32..157...786...3739....15574.....55410......170616.......465037

.2..8.44..280..2016..15574...115168....728078.....3793342.....16517460

.2..9.58..464..4608..55410...728078...8866257....88486476....701948916

.2.10.74..726..9582.170616..3793342..88486476..1799674094..28852930912

.2.11.92.1085.18446.465037.16517460.701948916.28852930912.976134459840

Links

R. H. Hardin, Table of n, a(n) for n = 1..220

Example

Some solutions for n=7 k=5
..0..0..0..1..1....0..0..0..1..1....0..0..1..1..1....0..0..0..1..1
..0..0..0..1..1....0..0..0..1..1....0..1..0..1..1....0..0..0..1..1
..0..0..0..1..1....1..1..1..0..1....0..1..1..0..1....0..1..1..0..1
..0..0..1..0..1....1..1..1..0..1....0..1..1..0..1....1..0..1..0..1
..0..1..0..0..1....1..1..1..1..0....0..1..1..1..0....1..0..1..1..0
..1..0..0..0..1....1..1..1..1..0....0..1..1..1..0....1..1..0..0..0
..1..1..1..1..0....1..1..1..1..0....1..0..0..0..0....1..1..0..0..0

Crossrefs

Column 3 is A003682

Sequence in context: A127417 A308622 A198897 * A309865 A128764 A324818

Adjacent sequences: A201372 A201373 A201374 * A201376 A201377 A201378

Keyword

nonn,tabl

Author

R. H. Hardin Nov 30 2011

Status

approved