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 A051242 #11 Apr 20 2013 03:05:19
%S A051242 2,10,1,12,4,3,38,6,8,5,42,18,11,7,9,52,22,13,16,15,17,56,24,14,19,32,
%T A051242 21,33,142,28,34,20,35,27,45,65,150,70,36,23,37,31,51,73,129,170,78,
%U A051242 39,25,41,64,63,85,153,257,178,82,40,26,44,67,128
%N A051242 Array T by antidiagonals; T(n,k)=k-th binary number d(1),...,d(j) for which exactly n digits d(i) satisfy d(i)=d(j+1-i) (n=0,1,2,...; k=1,2,3,..).
%e A051242 Antidiagonals: {2}; {10,1}; {12,4,3}; ...
%e A051242 Top row: {2,10,12,38,42,...}=A035928.
%K A051242 nonn,base,tabl
%O A051242 1,1
%A A051242 _Clark Kimberling_