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 A262129 #4 Sep 11 2015 19:32:36 %S A262129 1,1,1,3,9,45,224,1568,10763,96867,840122,9241342,96502325,1254530225, %T A262129 15299599194,229493987910,3199636182647,54393815104999, %U A262129 853245337600170,16211661414403230,282567703716447041,5933921778045387861,113771512251159523658 %N A262129 Number of permutations p of [n] such that the up-down signature of p has nonnegative partial sums with a maximal value <= 4. %H A262129 Alois P. Heinz, <a href="/A262129/b262129.txt">Table of n, a(n) for n = 0..400</a> %F A262129 a(n) = A262124(n,4). %Y A262129 Column k=4 of A262124. %K A262129 nonn %O A262129 0,4 %A A262129 _Alois P. Heinz_, Sep 11 2015