A202042 Number of zero-sum nX3 -1..1 arrays with every element unequal to at most two horizontal and vertical neighbors

7, 73, 415, 2921, 19541, 149149, 1067983, 8193025, 60897081, 469758219, 3566405667, 27631630057, 212463113105, 1652463728885, 12810745435213, 99982282638169, 779490730807285, 6102033983822007, 47767263490283739

Offset

1,1

Comments

Column 3 of A202047

Links

R. H. Hardin, Table of n, a(n) for n = 1..67

Example

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

Crossrefs

Sequence in context: A373685 A027017 A076106 * A294291 A318688 A117982

Adjacent sequences: A202039 A202040 A202041 * A202043 A202044 A202045

Keyword

nonn

Author

R. H. Hardin Dec 10 2011

Status

approved