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 A291888 #8 Nov 27 2024 11:59:22 %S A291888 1,4,19,69,252,855,2867,9339,30085,95524,300796,939228,2915481, %T A291888 9001380,27675779,84782673,258956584,788926699,2398385803,7277878707, %U A291888 22050326805,66718218120,201640080056,608808949752,1836608777233,5536482441124,16679237438035 %N A291888 Number of symmetrically unique Dyck paths of semilength n and height four. %H A291888 Alois P. Heinz, <a href="/A291888/b291888.txt">Table of n, a(n) for n = 4..1000</a> %H A291888 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (8,-19,-2,66,-76,3,30,-9). %F A291888 G.f.: x^4*(3*x^4-5*x^3+6*x^2-4*x+1)/((x-1)*(3*x-1)*(x^2-3*x+1)*(3*x^2-1)*(x^2+x-1)). %Y A291888 Column k=4 of A291883. %K A291888 nonn,easy %O A291888 4,2 %A A291888 _Alois P. Heinz_, Sep 05 2017