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 A209559 #8 Apr 26 2016 12:07:07 %S A209559 1,1,1,3,2,1,5,8,3,1,9,17,15,4,1,15,38,39,24,5,1,25,76,104,74,35,6,1, %T A209559 41,149,242,229,125,48,7,1,67,282,543,607,440,195,63,8,1,109,524,1159, %U A209559 1531,1308,769,287,80,9,1,177,957,2401,3631,3660,2533,1253,404 %N A209559 Triangle of coefficients of polynomials u(n,x) jointly generated with A209560; see the Formula section. %C A209559 For a discussion and guide to related arrays, see A208510. %F A209559 u(n,x)=x*u(n-1,x)+v(n-1,x), %F A209559 v(n,x)=u(n-1,x)+(x+1)*v(n-1,x) +1, %F A209559 where u(1,x)=1, v(1,x)=1. %e A209559 First five rows: %e A209559 1 %e A209559 1...1 %e A209559 3...2....1 %e A209559 5...8....3....1 %e A209559 9...17...15...4...1 %e A209559 First three polynomials v(n,x): 1, 1 + x, 3 + 2x + x^2. %t A209559 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209559 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x]; %t A209559 v[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A209559 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209559 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209559 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209559 TableForm[cu] %t A209559 Flatten[%] (* A209559 *) %t A209559 Table[Expand[v[n, x]], {n, 1, z}] %t A209559 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209559 TableForm[cv] %t A209559 Flatten[%] (* A209560 *) %Y A209559 Cf. A209560, A208510. %K A209559 nonn,tabl %O A209559 1,4 %A A209559 _Clark Kimberling_, Mar 10 2012