A185823 1/5 the number of n X 7 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.
65, 426928, 956312244, 2852526229300, 7662203273902712
Offset: 1
Keywords
Examples
Some solutions for 4 X 7 with a(1,1)=0 ..0..0..0..3..3..1..2....0..0..0..2..2..2..0....0..0..0..1..4..4..0 ..0..1..0..1..2..1..2....0..1..0..1..1..0..0....0..1..0..1..3..3..0 ..0..1..0..1..2..1..2....0..1..0..1..0..1..1....0..1..0..1..0..4..4 ..0..0..0..1..0..0..2....0..0..0..1..0..0..0....0..0..0..1..0..3..3
Crossrefs
Cf. A185825.
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