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A184096 Half the number of n X n toroidal binary arrays with each element having the sum of its vertical neighbors equal to the sum of its horizontal neighbors 0

%I

%S 1,2,7,18,31,98,127,450,511,1922,2047,7938,8191,32258,32767,130050,

%T 131071,522242,524287,2093058

%N Half the number of n X n toroidal binary arrays with each element having the sum of its vertical neighbors equal to the sum of its horizontal neighbors

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

%C Diagonal of A184097

%F Empirical G.f.: x*(1+2*x-2*x^2)*(1+2*x^2)/(1-x)/(1+x)/(1-2*x)/(1+2*x)/(1-2*x^2). [Colin Barker, Feb 17 2012]

%e Some solutions for 5X5

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

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

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 09 2011

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Last modified September 19 04:06 EDT 2020. Contains 337175 sequences. (Running on oeis4.)