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 A124221 #2 Mar 31 2012 13:23:38 %S A124221 1,2,4,8,0,14,2,22,9,1,0,32,25,5,2,44,54,16,12,0,2,0,58,100,38,42,2, %T A124221 13,2,1,74,167,75,110,9,51,15,7,1,0,3,0,92,259,131,240,25,146,63,28,5, %U A124221 5,24,2,1,3,112,380,210,462,54,340,193,80,16,29,111,18,11,25,0,2,0,0,1,4,0 %N A124221 Triangle read by rows: add A124222(n,k) to A124222(n-1,k). %C A124221 Row sums are powers of 2. Row sum sequence for A124222 is A001045. %F A124221 A124221(n,k) = A124222(n,k) + A124222(n-1,k) for n>0 %e A124221 A124222 begins %e A124221 0 %e A124221 1 %e A124221 1 %e A124221 3 %e A124221 5 0 %e A124221 9 2 %e A124221 13 7 1 0 %e A124221 so A124221 begins %e A124221 1 %e A124221 2 %e A124221 4 %e A124221 8 0 %e A124221 14 2 %e A124221 22 9 1 0 %Y A124221 Cf. A000079 A001045 A124222. %K A124221 easy,nonn,tabf %O A124221 1,2 %A A124221 _Alford Arnold_, Oct 23 2006