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 A291890 #6 Sep 09 2017 12:41:57 %S A291890 1,6,41,209,1005,4411,18546,74854,294293,1131635,4280686,15974526, %T A291890 58974616,215772740,783598381,2827768273,10149744903,36261522803, %U A291890 129027358151,457486923079,1617031493924,5699720240694,20040736126691,70308818376855,246171461366950 %N A291890 Number of symmetrically unique Dyck paths of semilength n and height six. %H A291890 Alois P. Heinz, <a href="/A291890/b291890.txt">Table of n, a(n) for n = 6..1000</a> %H A291890 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (12, -51, 66, 144, -540, 411, 510, -1006, 380, 282, -284, 84, -8). %F A291890 G.f.: x^6*(20*x^2-43*x^3+48*x^4-20*x^5+x^7-6*x+1) / ((2*x-1) *(2*x^2-4*x+1) *(x^3-2*x^2-x+1) *(x^3-6*x^2+5*x-1) *(2*x^4-4*x^2+1)). %Y A291890 Column k=6 of A291883. %K A291890 nonn,easy %O A291890 6,2 %A A291890 _Alois P. Heinz_, Sep 05 2017