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 A143753 #5 Mar 30 2012 18:51:59 %S A143753 3,8,5,15,12,24,7,21,35,16,32,48,9,27,45,63,20,40,60,80,11,33,55,77, %T A143753 99,24,48,72,96,120,13,39,65,91,117,143,28,56,84,112,140,168,15,45,75, %U A143753 105,135,165,195,32,64,96,128,160,192,224 %N A143753 Irregular triangle: A120070 read downwards antidiagonals. %C A143753 The triangle in this rearrangement contains 1, 1, 2, 2, 3, 3, 4, 4,... = floor((n+1)/2) entries in row n. %C A143753 The first differences between terms in row n are A005843(n+2). %e A143753 3; %e A143753 8; %e A143753 5,15; %e A143753 12,24; %e A143753 7,21,35; %e A143753 16,32,48; %K A143753 nonn,easy,tabf %O A143753 1,1 %A A143753 _Paul Curtz_, Aug 31 2008