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 A262127 #4 Sep 11 2015 18:47:33 %S A262127 1,1,3,57,778,47673,1477381,196352061,10896848134,2539183745028, %T A262127 220995092995233,79875004816604671,10032237471596350240, %U A262127 5198811549997063847059,890008776794671492878641,626002734896306246681963237,140112228518254335504033414806 %N A262127 Number of permutations p of [2n] such that the up-down signature of p has nonnegative partial sums with a maximal value of n. %H A262127 Alois P. Heinz, <a href="/A262127/b262127.txt">Table of n, a(n) for n = 0..50</a> %F A262127 a(n) = A262125(2n,n). %Y A262127 Cf. A262125. %K A262127 nonn %O A262127 0,3 %A A262127 _Alois P. Heinz_, Sep 11 2015