|
|
A211043
|
|
1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors.
|
|
0
|
|
|
0, 1, 8, 156, 7480, 898680, 266674964, 196750879896, 360466213243792, 1640421325318165822, 18541481770815952051304, 520535380394250894532873968, 36296751650483051319011293939152
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
EXAMPLE
|
Some solutions for n=4
..2..2..1..1....1..1..0..1....0..0..1..2....2..2..1..1....2..2..1..1
..2..2..1..0....1..0..0..1....0..1..1..2....2..2..0..2....2..1..1..1
..1..1..1..0....0..0..2..2....1..1..2..2....1..0..0..2....1..1..0..0
..1..0..0..0....1..1..2..2....2..2..2..2....1..2..2..2....1..1..0..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|