A202042 - OEIS

%I #5 Mar 31 2012 12:36:46

%S 7,73,415,2921,19541,149149,1067983,8193025,60897081,469758219,

%T 3566405667,27631630057,212463113105,1652463728885,12810745435213,

%U 99982282638169,779490730807285,6102033983822007,47767263490283739

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

%C Column 3 of A202047

%H R. H. Hardin, <a href="/A202042/b202042.txt">Table of n, a(n) for n = 1..67</a>

%e Some solutions for n=5

%e ..1.-1..0....1..0..0...-1.-1..1....1..1.-1...-1..1..0....1.-1.-1...-1..0..1

%e .-1.-1.-1....1..0..0...-1..1..1...-1.-1.-1....1..1.-1....0..0.-1....1..0..1

%e ..1.-1.-1....0..0..0...-1..1..1....1..1..1....1..1.-1....0..0..0....1..0..0

%e ..1..1..1...-1.-1.-1...-1..0..0....1.-1.-1...-1.-1.-1....0..0..0....0..0..0

%e ..0..0..1....0..0..1....0..0..0....1.-1..0....0..0..1....1..1..0...-1.-1.-1

%K nonn

%O 1,1

%A _R. H. Hardin_ Dec 10 2011