|
|
A211051
|
|
1/3 the number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors
|
|
0
|
|
|
1, 5, 45, 801, 27967, 1940165, 265677267, 71849269093, 38284388785363, 40154074645523977, 82859490626738386321, 336329579954192837096611, 2685093328682215861465741329
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
Some solutions for n=4
..0..1..0..0....0..1..0..1....2..0..2..0....2..2..2..2....2..1..2..2
..1..0..0..0....1..2..1..2....0..1..0..1....2..0..1..2....1..2..2..2
..0..0..2..1....0..1..2..0....2..0..1..0....2..1..2..2....2..2..2..2
..0..0..1..2....1..2..0..1....0..1..0..2....2..2..2..0....2..2..2..2
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|