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 A048212 #6 Mar 30 2012 18:56:54
%S A048212 2,1,3,4,5,7,6,10,11,13,8,14,18,19,21,9,17,23,27,28,30,12,21,29,35,39,
%T A048212 40,42,15,27,36,44,50,54,55,57,16,31,43,52,60,66,70,71,73,20,36,51,63,
%U A048212 72,80,86,90,91,93,22,42,58,73,85,94,102,108
%N A048212 Triangular array T read by rows: T(i,j)=b(i+1)-b(i+1-j); j=1,2,...,i; i=1,2,3,...; b=A004979.
%e A048212 Rows: {2}; {1,3}; {4,5,7}; ...
%K A048212 nonn,tabl
%O A048212 1,1
%A A048212 _Clark Kimberling_