login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A188400 Number of (6*n) X 6 binary arrays with rows in nonincreasing order, n ones in every column and no more than 2 ones in any row. 2
1, 76, 2578, 44288, 478711, 3710272, 22393101, 111200600, 472211360, 1763603560, 5916521021, 18121655192, 51328536740, 135834620472, 338676787932, 801091475448, 1808025242415, 3912600581712, 8152010122276, 16411466716600, 32022153082291, 60720959942432, 112158519503545 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of 6 X 6 symmetric matrices with nonnegative integer entries and all row and column sums n. - Andrew Howroyd, Apr 07 2020

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..50

EXAMPLE

Some solutions for 12X6

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

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

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

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

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

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

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

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

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

..0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0

..0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0

..0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..0

CROSSREFS

Column 6 of A188403.

Sequence in context: A278092 A153177 A166191 * A205918 A261574 A017792

Adjacent sequences:  A188397 A188398 A188399 * A188401 A188402 A188403

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 30 2011

EXTENSIONS

a(0)=1 prepended and terms a(17) and beyond from Andrew Howroyd, Apr 07 2020

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 26 06:32 EDT 2022. Contains 356987 sequences. (Running on oeis4.)