login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A180987 T(n,k)=number of nXk binary matrices with rows in lexicographically nonincreasing order and columns in lexicographically strictly increasing order 2
2, 1, 3, 0, 3, 4, 0, 1, 6, 5, 0, 0, 4, 10, 6, 0, 0, 1, 10, 15, 7, 0, 0, 0, 5, 20, 21, 8, 0, 0, 0, 1, 15, 35, 28, 9, 0, 0, 0, 0, 6, 35, 56, 36, 10, 0, 0, 0, 0, 1, 21, 70, 84, 45, 11, 0, 0, 0, 0, 0, 7, 56, 126, 120, 55, 12, 0, 0, 0, 0, 0, 1, 28, 126, 210, 165, 66, 13, 0, 0, 0, 0, 0, 0, 8, 84, 252, 330 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Table starts

..2...1...0....0....0....0.....0.....0.....0....0....0....0...0

..3...3...1....0....0....0.....0.....0.....0....0....0....0...0

..4...6...4....1....0....0.....0.....0.....0....0....0....0...0

..5..10..10....5....1....0.....0.....0.....0....0....0....0...0

..6..15..20...15....6....1.....0.....0.....0....0....0....0...0

..7..21..35...35...21....7.....1.....0.....0....0....0....0...0

..8..28..56...70...56...28.....8.....1.....0....0....0....0...0

..9..36..84..126..126...84....36.....9.....1....0....0....0...0

.10..45.120..210..252..210...120....45....10....1....0....0...0

.11..55.165..330..462..462...330...165....55...11....1....0...0

.12..66.220..495..792..924...792...495...220...66...12....1...0

.13..78.286..715.1287.1716..1716..1287...715..286...78...13...1

.14..91.364.1001.2002.3003..3432..3003..2002.1001..364...91..14

.15.105.455.1365.3003.5005..6435..6435..5005.3003.1365..455.105

.16.120.560.1820.4368.8008.11440.12870.11440.8008.4368.1820.560

LINKS

R. H. Hardin, Table of n, a(n) for n=1..478

FORMULA

Conjecture: T(n,k) = A180986(n-k+1,k), k<=n . [From R. J. Mathar, Oct 18 2010]

EXAMPLE

All solutions for 3X3

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

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

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

CROSSREFS

Sequence in context: A141198 A239621 A231204 * A092093 A197386 A096269

Adjacent sequences:  A180984 A180985 A180986 * A180988 A180989 A180990

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Sep 30 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 11 01:12 EDT 2020. Contains 335600 sequences. (Running on oeis4.)