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 A026970 #12 Oct 20 2019 16:23:00
%S A026970 1,3,8,25,60,147,336,765,1700,3751,8184,17745,38220,81915,174752,
%T A026970 371365,786420,1660239,3495240,7340025,15379100,32156323,67108848,
%U A026970 139810125,290805060,603979767,1252698776,2594876065,5368709100
%N A026970 a(n) = Sum_{k=0..n} (k+1) * A026637(n,k).
%F A026970 Conjectures from _Colin Barker_, Feb 18 2016: (Start)
%F A026970 a(n) = -((-1)^n-2^(n+2)+3)*(n+2)/6 for n>0.
%F A026970 a(n) = 4*a(n-1)-2*a(n-2)-8*a(n-3)+7*a(n-4)+4*a(n-5)-4*a(n-6) for n>6.
%F A026970 G.f.: (1-x-2*x^2+7*x^3-7*x^4-4*x^5+4*x^6) / ((1-x)^2*(1+x)^2*(1-2*x)^2).
%F A026970 (End)
%K A026970 nonn
%O A026970 0,2
%A A026970 _Clark Kimberling_