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 A193049 #8 Jun 13 2015 00:53:55 %S A193049 0,1,1,2,4,12,37,105,268,625,1355,2772,5414,10188,18605,33161,57954, %T A193049 99683,169265,284452,474066,784852,1292567,2119923,3465620,5651323, %U A193049 9197673,14947276,24263704,39353486,63787101,103341963,167366400,270986619 %N A193049 Coefficient of x in the reduction by x^2->x+1 of the polynomial p(n,x) defined at Comments. %C A193049 The titular polynomials are defined recursively: p(n,x)=x*p(n-1,x)+n(4-5*n^2+n^4)/120, with p(0,x)=1. For an introduction to reductions of polynomials by substitutions such as x^2->x+1, see A192232 and A192744. %H A193049 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (7,-20,29,-20,1,8,-5,1). %F A193049 a(n)=7*a(n-1)-20*a(n-2)+29*a(n-3)-20*a(n-4)+*a(n-5)+8*a(n-6)-5*a(n-7)+a(n-8). %F A193049 G.f.: -x*(x^2-x+1)*(x^4-5*x^3+9*x^2-5*x+1) / ( (x^2+x-1)*(x-1)^6 ). - _R. J. Mathar_, May 12 2014 %t A193049 (See A193048.) %Y A193049 Cf. A192232, A192744, A192951, A193048. %K A193049 nonn %O A193049 0,4 %A A193049 _Clark Kimberling_, Jul 15 2011