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A201955
Number of zero-sum n X 2 -3..3 arrays with every element unequal to at most two horizontal and vertical neighbors.
1
7, 231, 1587, 17903, 194633, 2232183, 25952953, 305979795, 3640250461, 43624267941, 525774918227, 6366440653727, 77388201173481, 943784967491137, 11542145313593503, 141498452574240619, 1738344524754583621
OFFSET
1,1
COMMENTS
Column 2 of A201958.
LINKS
EXAMPLE
Some solutions for n=4
..2..3...-3.-3...-2.-3...-2..3...-2..1....2.-3....2.-3....2..0...-3.-1....1.-2
..0..0....2..2....1..1....0..0...-2..0....1..1....3.-3....0.-1....3..0....0..0
.-2.-2...-1.-1....2..2....1..1....2..0....0..0....3..0....0.-1....3..0....0..0
.-2..1....3..1....0.-1...-1.-2....2.-1...-1..0...-2..0....3.-3...-2..0....3.-2
CROSSREFS
Cf. A201958.
Sequence in context: A221495 A343128 A142116 * A081618 A285369 A287042
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 06 2011
STATUS
approved