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 A306504 #17 Feb 21 2019 09:48:59
%S A306504 1,2,5,16,46,128,366,1048,2983,8498,24235,69088,196924,561360,1600252,
%T A306504 4561680,13003565,37068242,105667377,301217072,858654442,2447694896,
%U A306504 6977439850,19890006440,56698785235,161626505250,460735217111,1313379512256,3743941595128,10672542499296
%N A306504 Expansion of 1/(x^6+2*x^5-x^4-4*x^3-x^2-2*x+1).
%H A306504 Seiichi Manyama, <a href="/A306504/b306504.txt">Table of n, a(n) for n = 0..2000</a>
%H A306504 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,4,1,-2,-1).
%F A306504 a(n) = 2*a(n-1) + a(n-2) + 4*a(n-3) + a(n-4) - 2*a(n-5) - a(n-6).
%o A306504 (PARI) N=66; x='x+O('x^N); Vec(1/(x^6+2*x^5-x^4-4*x^3-x^2-2*x+1))
%Y A306504 Self-convolution of A306463.
%K A306504 nonn
%O A306504 0,2
%A A306504 _Seiichi Manyama_, Feb 20 2019