A202043 Number of zero-sum nX4 -1..1 arrays with every element unequal to at most two horizontal and vertical neighbors

19, 335, 2921, 31753, 359017, 4188917, 49553277, 594443301, 7206865523, 88120417529, 1084547246367, 13417760493253, 166705101517923, 2078489858665207, 25992085202674059, 325869090446388117

Offset

1,1

Comments

Column 4 of A202047

Links

R. H. Hardin, Table of n, a(n) for n = 1..31

Example

Some solutions for n=4
..1..1.-1.-1....1..1.-1..0...-1..1..1.-1....1.-1..1..1....0..1..1..0
.-1..1..1.-1....0.-1.-1..0....1..0..0.-1....1.-1..0..0....0..0..0..0
.-1..1..1.-1....0.-1..1..1....1..0..0.-1....1.-1..0..0....1.-1.-1.-1
.-1.-1..1..1...-1.-1..1..1....1..1.-1.-1...-1.-1..0..0....1.-1..0..0

Crossrefs

Sequence in context: A121324 A093973 A345963 * A142549 A049629 A162805

Adjacent sequences: A202040 A202041 A202042 * A202044 A202045 A202046

Keyword

nonn

Author

R. H. Hardin Dec 10 2011

Status

approved