A201797 Number of zero-sum nX2 -2..2 arrays with every element unequal to at most two horizontal and vertical neighbors

5, 85, 455, 3617, 28625, 235827, 1972115, 16703881, 142672901, 1226999941, 10610923603, 92180196507, 803840798219, 7032319990027, 61691173120353, 542479698511869, 4780243712781261, 42200307665852185, 373156481784589911

Offset

1,1

Comments

Column 2 of A201803

Links

R. H. Hardin, Table of n, a(n) for n = 1..126

Example

Some solutions for n=5
..2.-1...-2..2...-2..2...-1..2...-2..1....1..2....2..2....0..0....0..0...-1.-2
..2.-1...-2..0....1..1...-1..2....2.-1...-2.-2...-2.-2....2..2....2.-1...-1.-2
..0..0...-2..0....0..0....1.-2....2.-1....2.-2....2..0....0..0....2.-1....2..0
..0..0....2..2...-1.-1....1.-2...-2.-2....2.-2....2..0....0.-1...-1.-1....2..0
..0.-2....1.-1....2.-2....2.-2....1..2....2.-1...-2.-2...-2.-1...-1..1....0..2

Crossrefs

Sequence in context: A137083 A198586 A121290 * A012743 A359234 A139744

Adjacent sequences: A201794 A201795 A201796 * A201798 A201799 A201800

Keyword

nonn

Author

R. H. Hardin Dec 05 2011

Status

approved