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 A175896 #8 Apr 20 2023 18:00:28
%S A175896 1,2,9,57,396,2948,23016,185838,1539066,13001677,111600446,970550862,
%T A175896 8533427593,75728797781,677427655798,6102015206945,55299451023428,
%U A175896 503847366381836,4612663920303329,42409513650507927,391425863599784588
%N A175896 Number of lattice paths from (0,0) to (n,n) using steps S={(k,0),(0,k),(1,1)|0<k<=3} which never go above the line y-x.
%Y A175896 Cf. A006318, A175895.
%K A175896 nonn
%O A175896 0,2
%A A175896 _Eric Werley_, Dec 05 2010