A184101 - OEIS

%I #5 Mar 31 2012 12:35:56

%S 1,1,1,1,4,1,1,1,1,1,1,4,85,4,1,1,1,1,1,1,1,1,4,1,484,1,4,1,1,1,85,1,

%T 1,85,1,1,1,4,1,4,3661,4,1,4,1,1,1,1,1,1,1,1,1,1,1,1,4,85,484,1,28900,

%U 1,484,85,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,4,1,4,1,4,137845,4,1,4,1,4,1,1,1

%N T(n,k)=One quarter the number of nXk toroidal 0..3 arrays with each element having the sum of its vertical neighbors equal to the sum of its horizontal neighbors

%C One quarter the number of solutions in 0..3 of a 1-d velocity-one wave equation utt=uxx on a periodic grid

%C Table starts

%C .1.1..1...1....1.....1......1.......1..1....1.1.....1.1.1..1.1.1

%C .1.4..1...4....1.....4......1.......4..1....4.1.....4.1.4..1.4

%C .1.1.85...1....1....85......1.......1.85....1.1....85.1.1.85

%C .1.4..1.484....1.....4......1.....484..1....4.1...484.1.4

%C .1.1..1...1.3661.....1......1.......1..1.3661.1.....1.1

%C .1.4.85...4....1.28900......1.......4.85....4.1.28900

%C .1.1..1...1....1.....1.137845.......1..1....1.1

%C .1.4..1.484....1.....4......1.1322500..1....4

%C .1.1.85...1....1....85......1.......1

%C .1.4..1...4.3661.....4......1

%H R. H. Hardin, <a href="/A184101/b184101.txt">Table of n, a(n) for n = 1..144</a>

%e Some solutions for 9X3

%e ..3..0..3....1..1..1....3..2..0....2..1..1....1..0..2....3..1..2....1..2..1

%e ..3..3..0....0..1..2....1..1..3....2..2..0....2..1..0....0..3..3....1..2..1

%e ..0..3..3....2..1..0....1..2..2....0..1..3....0..2..1....3..2..1....2..0..2

%e ..3..0..3....1..1..1....3..2..0....2..1..1....1..0..2....3..1..2....1..2..1

%e ..3..3..0....0..1..2....1..1..3....2..2..0....2..1..0....0..3..3....1..2..1

%e ..0..3..3....2..1..0....1..2..2....0..1..3....0..2..1....3..2..1....2..0..2

%e ..3..0..3....1..1..1....3..2..0....2..1..1....1..0..2....3..1..2....1..2..1

%e ..3..3..0....0..1..2....1..1..3....2..2..0....2..1..0....0..3..3....1..2..1

%e ..0..3..3....2..1..0....1..2..2....0..1..3....0..2..1....3..2..1....2..0..2

%K nonn,tabl

%O 1,5

%A _R. H. Hardin_ Jan 09 2011