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 A209575 #5 Mar 30 2012 18:58:15 %S A209575 1,1,1,1,5,1,1,5,15,1,1,5,23,37,1,1,5,23,89,83,1,1,5,23,105,295,177,1, %T A209575 1,5,23,105,447,873,367,1,1,5,23,105,479,1721,2383,749,1,1,5,23,105, %U A209575 479,2121,6015,6137,1515,1,1,5,23,105,479,2185,8847,19369,15143 %N A209575 Triangle of coefficients of polynomials u(n,x) jointly generated with A209576; see the Formula section. %C A209575 For a discussion and guide to related arrays, see A208510. %F A209575 u(n,x)=x*u(n-1,x)+v(n-1,x), %F A209575 v(n,x)=2x*u(n-1,x)+2x*v(n-1,x)+1, %F A209575 where u(1,x)=1, v(1,x)=1. %e A209575 First five rows: %e A209575 1 %e A209575 1...1 %e A209575 1...5...1 %e A209575 1...5...15...1 %e A209575 1...5...23...37...1 %e A209575 First three polynomials v(n,x): 1, 1 + x, 1 + 5x + x^2. %t A209575 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209575 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x]; %t A209575 v[n_, x_] := 2 x*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A209575 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209575 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209575 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209575 TableForm[cu] %t A209575 Flatten[%] (* A209575 *) %t A209575 Table[Expand[v[n, x]], {n, 1, z}] %t A209575 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209575 TableForm[cv] %t A209575 Flatten[%] (* A209576 *) %Y A209575 Cf. A209576, A208510. %K A209575 nonn,tabl %O A209575 1,5 %A A209575 _Clark Kimberling_, Mar 11 2012