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 A125700 #13 Feb 16 2025 08:33:04
%S A125700 1,3,15,77,494,4068
%N A125700 Number of connected categories with n more morphisms than objects.
%H A125700 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Category.html">Category</a>
%F A125700 a(n) = Sum_{k=1..n+1} A125699(n+k,k).
%Y A125700 Cf. A125696, A125699, A125701.
%K A125700 nonn,hard,more
%O A125700 0,2
%A A125700 _Franklin T. Adams-Watters_ and _Christian G. Bower_, Jan 05 2007
%E A125700 a(4)-a(5) from _Ben Spitz_, Aug 30 2023