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 A026573 #6 Jun 23 2013 12:06:25 %S A026573 1,3,12,34,103,281,778,2072,5524,14488,37918,98474,255137,658351, %T A026573 1695542,4356520,11177720,28637452,73294698,187412326,478861373, %U A026573 1222765699,3120722598,7961152560,20302100415,51757554237 %N A026573 a(n)=T(n,n-4), T given by A026568. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=4. %F A026573 Conjecture: -2*(n-4)*(n+4)*a(n) +(5*n^2-5*n-46)*a(n-1) +(4*n^2+n+18)*a(n-2) +(-11*n^2+24*n-16)*a(n-3) +2*(n-2)*(2*n-5)*a(n-4)=0. - _R. J. Mathar_, Jun 23 2013 %K A026573 nonn %O A026573 4,2 %A A026573 _Clark Kimberling_