login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 0
1, 2, 6, 71, 2403, 238535, 73506103, 64732546521, 189964969385932, 1647943050926969975 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Diagonal of A180983

LINKS

Table of n, a(n) for n=1..10.

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

Sequence in context: A000896 A103527 A239543 * A195690 A171582 A152885

Adjacent sequences:  A180979 A180980 A180981 * A180983 A180984 A180985

KEYWORD

nonn

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 November 15 01:15 EST 2019. Contains 329142 sequences. (Running on oeis4.)