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A188408 Number of (7*n) X n binary arrays with rows in nonincreasing order, 7 ones in every column and no more than 2 ones in any row. 1
1, 1, 8, 154, 7340, 681460, 111200600, 29445929253, 11930327925108, 7061916086148812, 5884543061841730064, 6695191219474600587460, 10138670050730337096234992, 19996250425584243540741431296, 50416254105984511132422687541856, 159887463958073530310081258765881180 (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 7. - Andrew Howroyd, Apr 07 2020
LINKS
Table of n, a(n) for n=0..15.
EXAMPLE
All solutions for 14X2
..1..1....1..1....1..1....1..1....1..1....1..1....1..0....1..1
..1..1....1..1....1..1....1..1....1..1....1..0....1..0....1..1
..1..0....1..1....1..1....1..1....1..1....1..0....1..0....1..1
..1..0....1..1....1..1....1..1....1..1....1..0....1..0....1..0
..1..0....1..0....1..1....1..1....1..1....1..0....1..0....1..0
..1..0....1..0....1..1....1..0....1..1....1..0....1..0....1..0
..1..0....1..0....1..0....1..0....1..1....1..0....1..0....1..0
..0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1
..0..1....0..1....0..0....0..1....0..0....0..1....0..1....0..1
..0..1....0..1....0..0....0..0....0..0....0..1....0..1....0..1
..0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..1
..0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..0
..0..0....0..0....0..0....0..0....0..0....0..1....0..1....0..0
..0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0
CROSSREFS
Row 7 of A188403.
Sequence in context: A356900 A191908 A302959 * A089669 A288682 A268543
Adjacent sequences: A188405 A188406 A188407 * A188409 A188410 A188411
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 30 2011
EXTENSIONS
a(0)=1 prepended and terms a(9) and beyond from Andrew Howroyd, Apr 06 2020
STATUS
approved

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Last modified August 31 11:25 EDT 2024. Contains 375560 sequences. (Running on oeis4.)