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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A188406 Number of (5*n) X n binary arrays with rows in nonincreasing order, 5 ones in every column and no more than 2 ones in any row. 1
 1, 1, 6, 69, 1620, 62781, 3710272, 313568636, 36218801244, 5518184697792, 1078258692423672, 264082675302603684, 79537577428138854144, 28988656113108616134732, 12610397520409429024276176, 6469939930732195901177163384, 3874562148530193751600746715440, 2683567291732998871830525552934800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 5. - Andrew Howroyd, Apr 07 2020 LINKS EXAMPLE All solutions for 10X2 ..1..1....1..1....1..1....1..1....1..0....1..1 ..1..1....1..0....1..1....1..1....1..0....1..1 ..1..1....1..0....1..1....1..0....1..0....1..1 ..1..1....1..0....1..1....1..0....1..0....1..0 ..1..0....1..0....1..1....1..0....1..0....1..0 ..0..1....0..1....0..0....0..1....0..1....0..1 ..0..0....0..1....0..0....0..1....0..1....0..1 ..0..0....0..1....0..0....0..1....0..1....0..0 ..0..0....0..1....0..0....0..0....0..1....0..0 ..0..0....0..0....0..0....0..0....0..1....0..0 CROSSREFS Row 5 of A188403. Sequence in context: A235328 A296783 A218683 * A048708 A286527 A104900 Adjacent sequences:  A188403 A188404 A188405 * A188407 A188408 A188409 KEYWORD nonn AUTHOR R. H. Hardin, Mar 30 2011 EXTENSIONS a(0)=1 prepended and terms a(10) 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 21 01:46 EDT 2021. Contains 347596 sequences. (Running on oeis4.)