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 A171875 #4 Jun 22 2022 00:40:48 %S A171875 0,0,1,3,17,74,358,1631,7563,34751,160807 %N A171875 Subdiagonal of triangle A171871: Classifications of N elements containing exactly N-2 binary partitions. %H A171875 R. Munafo, <a href="http://mrob.com/pub/math/seq-a005646.html">Classifications of N Elements</a> %Y A171875 Cf. A171871. %K A171875 nonn %O A171875 2,4 %A A171875 _Robert Munafo_, Jan 21 2010