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 A052253 #4 Mar 30 2012 17:36:31 %S A052253 1,1,1,2,1,1,3,3,2,1,8,5,4,2,1,16,13,9,6,3,1,41,28,21,13,8,3,1,98,71, %T A052253 49,33,20,10,4,1,250,174,121,79,50,27,13,4,1,631,445,304,201,127,74, %U A052253 38,16,5,1,1646,1137,776,510,325,192,106,49,19,5,1,4285,2974 %N A052253 Triangle T(n,k) (n >= 1, k >= 1) giving filtration of bigrading of Hopf algebra of rooted trees. %H A052253 D. J. Broadhurst and D. Kreimer, <a href="http://arXiv.org/abs/hep-th/0001202">Towards cohomology of renormalization...</a> %e A052253 1; 1,1; 2,1,1; 3,3,2,1; 8,5,4,2,1; ... %Y A052253 Cf. A052250. %K A052253 nonn,nice,tabl %O A052253 0,4 %A A052253 _David Broadhurst_, Feb 05 2000