%N Negabinary numbral addition table.
%C Every negabinary numbral appears infinitely often (since every signed integer can be represented as a sum of two signed integers in infinitely many ways).
%H A. Frosini and S. Rinaldi, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL9/Frosini/fros2.html">On the Sequence A079500 and Its Combinatorial Interpretations</a>, J. Integer Seq., Vol. 9 (2006), Article 06.3.1.
%e a(4)=6 since a(4) corresponds to the table entry for +=1+1=2=4-2=.
%Y Cf. A005351, A005352, A057893, A057894.
%A _Marc LeBrun_, Sep 25 2000