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 A026975 #12 Oct 20 2019 19:48:54
%S A026975 1,3,10,25,66,154,392,882,2180,4796,11640,25220,60424,129480,307264,
%T A026975 652936,1538064,3247024,7604000,15968400,37217312,77818016,180652416,
%U A026975 376359200,870795328,1808574912,4172640640,8643327040
%N A026975 a(n) = Sum_{k=0..n} (k+1) * A026648(n,k).
%F A026975 Conjectures from _Colin Barker_, Feb 18 2016: (Start)
%F A026975 a(n) = 8*a(n-2)-12*a(n-4)-16*a(n-6)-4*a(n-8) for n>7.
%F A026975 G.f.: (1+3*x+2*x^2+x^3-2*x^4-10*x^5-2*x^7) / (1-4*x^2-2*x^4)^2.
%F A026975 (End)
%K A026975 nonn
%O A026975 0,2
%A A026975 _Clark Kimberling_