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A269821
Number of n X n 0..4 arrays with some element plus some horizontally, diagonally, antidiagonally or vertically adjacent neighbor totalling four exactly once.
0
0, 216, 103296, 240637408, 2840332868960, 190428267451649488, 74703200829032822656704, 174692108176538512510958268440
OFFSET
1,2
COMMENTS
Diagonal of A269829.
EXAMPLE
Some solutions for n=3
..2..3..2. .3..4..4. .3..2..0. .4..4..3. .0..2..1. .0..4..2. .3..2..0
..1..4..3. .2..4..2. .3..0..0. .3..2..4. .3..3..0. .3..3..4. .1..0..1
..1..2..3. .4..3..2. .4..2..3. .1..4..1. .0..3..3. .2..4..4. .0..1..2
CROSSREFS
Cf. A269829.
Sequence in context: A124009 A134358 A167127 * A268364 A358657 A048100
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 05 2016
STATUS
approved