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 A115635 #12 Dec 14 2023 05:32:00
%S A115635 1,1,-5,0,1,-3,-1,0,-3,1,-1,-4,1,1,-5,0,1,-3,-1,0,-3,1,-1,-4,1,1,-5,0,
%T A115635 1,-3,-1,0,-3,1,-1,-4,1,1,-5,0,1,-3,-1,0,-3,1,-1,-4,1,1,-5,0,1,-3,-1,
%U A115635 0,-3,1,-1,-4,1,1,-5,0,1,-3,-1,0,-3,1,-1,-4
%N A115635 Periodic {1,1,-5,0,1,-3,-1,0,-3,1,-1,-4}.
%C A115635 Diagonal sums of number triangle A115633.
%H A115635 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,0,1,1,1).
%F A115635 G.f.: (1+2x-3x^2-4x^3-5x^4-4x^5)/((1-x^3)*(1+x+x^2+x^3)); a(n)=sum{k=0..floor(n/2), A115633(n-k, k)}.
%K A115635 easy,sign
%O A115635 0,3
%A A115635 _Paul Barry_, Jan 27 2006