%I #5 Mar 31 2012 12:36:45
%S 0,1,1,1,5,1,3,25,25,3,1,97,125,97,1,9,411,2019,2019,411,9,7,1897,
%T 17031,54773,17031,1897,7,25,8741,259811,1566319,1566319,259811,8741,
%U 25,25,41689,2809217,47249907,109797321,47249907,2809217,41689,25,83,201985
%N T(n,k)=Number of zero-sum nXk -1..1 arrays with every element equal to at least one horizontal or vertical neighbor
%C Table starts
%C ..0......1..........1.............3..............1...............9
%C ..1......5.........25............97............411............1897
%C ..1.....25........125..........2019..........17031..........259811
%C ..3.....97.......2019.........54773........1566319........47249907
%C ..1....411......17031.......1566319......109797321......8964073263
%C ..9...1897.....259811......47249907.....8964073263...1759241274383
%C ..7...8741....2809217....1459651671...697824874477.350714115254871
%C .25..41689...38543397...45844870481.56238345975057
%C .25.201985..461143387.1455414376611
%C .83.987407.6074619247
%H R. H. Hardin, <a href="/A201847/b201847.txt">Table of n, a(n) for n = 1..83</a>
%e Some solutions for n=4 k=4
%e .-1..0..0..0...-1..1..0..0...-1.-1..1..1....0.-1..1..1...-1..0..1.-1
%e .-1.-1.-1..0...-1..1.-1.-1...-1..1..0..0....0.-1..0..0...-1..0..1.-1
%e ..1..1..1..1....0..0..1..0....1..1..0..0....0..0..1.-1....0..0.-1.-1
%e ..0..0..0..0....0..0..1..0....1.-1.-1.-1....0..0..1.-1....1..1..1..1
%K nonn,tabl
%O 1,5
%A _R. H. Hardin_ Dec 06 2011