|
| |
|
|
A211040
|
|
1/3 the number of n X n 0..2 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors
|
|
0
|
|
|
|
1, 4, 40, 928, 45128, 4945168, 1207742160, 655725571768, 791701825710768, 2127149017683661104, 12717092443922120808584, 169157473880575759274475472, 5006302388939519643670779061032
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
|
|
|
EXAMPLE
|
Some solutions for n=4
..2..1..2..2....0..1..0..2....1..0..0..1....2..0..2..1....1..0..1..0
..1..0..1..1....1..2..0..1....0..1..2..1....0..1..0..0....0..2..0..2
..2..1..0..2....0..0..2..1....0..2..0..2....2..0..2..1....1..0..2..1
..2..1..2..0....2..1..1..2....1..1..2..0....1..0..1..0....0..2..1..2
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
