This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A057893 #3 Mar 30 2012 17:38:10 %S A057893 0,0,0,0,1,0,0,2,2,0,0,3,4,3,0,0,4,6,6,4,0,0,5,8,1,8,5,0,0,6,10,12,12, %T A057893 10,6,0,0,7,12,15,16,15,12,7,0,0,8,14,2,20,20,2,14,8,0,0,9,16,13,24, %U A057893 105,24,13,16,9,0,0,10,18,24,28,30,30,28,24,18,10,0,0,11,20,27,32,19,4 %N A057893 Negabinary numbral multiplication table. %C A057893 Units are [1]=1 and [3]=-1. %e A057893 a(17)=6 since a(17) corresponds to the table entry for [3]+[2]=-1*-2=2=4-2=[6] %Y A057893 Cf. A005351, A005352, A057892, A057894. %K A057893 easy,nonn,tabl %O A057893 0,8 %A A057893 _Marc LeBrun_, Sep 25 2000