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 A141477 #4 Jul 20 2017 23:33:40 %S A141477 1,1,3,7,29,129,763,5191 %N A141477 Sum of southeast diagonals of A141476. %Y A141477 Cf. A082096. %K A141477 nonn %O A141477 0,3 %A A141477 _Paul Curtz_, Aug 09 2008