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 A209579 #5 Mar 30 2012 18:58:15 %S A209579 1,1,1,2,3,1,2,6,6,1,3,9,14,10,1,3,14,28,29,15,1,4,18,48,71,55,21,1,4, %T A209579 25,75,139,158,97,28,1,5,30,112,251,356,321,161,36,1,5,39,156,413,724, %U A209579 828,609,254,45,1,6,45,215,645,1321,1874,1782,1094,384,55,1,6 %N A209579 Triangle of coefficients of polynomials u(n,x) jointly generated with A209580; see the Formula section. %C A209579 For a discussion and guide to related arrays, see A208510. %F A209579 u(n,x)=x*u(n-1,x)+v(n-1,x), %F A209579 v(n,x)=(x+1)*u(n-1,x)+x*v(n-1,x)+1, %F A209579 where u(1,x)=1, v(1,x)=1. %e A209579 First five rows: %e A209579 1 %e A209579 1...1 %e A209579 2...3....1 %e A209579 2...6....6....1 %e A209579 3...9....14...10...1 %e A209579 First three polynomials v(n,x): 1, 1 + x, 2 + 3x + x^2. %t A209579 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209579 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x]; %t A209579 v[n_, x_] := (x + 1)*u[n - 1, x] + x*v[n - 1, x] + 1; %t A209579 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209579 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209579 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209579 TableForm[cu] %t A209579 Flatten[%] (* A209579 *) %t A209579 Table[Expand[v[n, x]], {n, 1, z}] %t A209579 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209579 TableForm[cv] %t A209579 Flatten[%] (* A209580 *) %Y A209579 Cf. A209580, A208510. %K A209579 nonn,tabl %O A209579 1,4 %A A209579 _Clark Kimberling_, Mar 11 2012