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 A209576 #6 Mar 30 2012 18:58:15 %S A209576 1,1,4,1,4,10,1,4,18,22,1,4,18,66,46,1,4,18,82,206,94,1,4,18,82,342, %T A209576 578,190,1,4,18,82,374,1274,1510,382,1,4,18,82,374,1642,4294,3754,766, %U A209576 1,4,18,82,374,1706,6726,13354,9006,1534,1,4,18,82,374,1706 %N A209576 Triangle of coefficients of polynomials v(n,x) jointly generated with A209575; see the Formula section. %C A209576 For a discussion and guide to related arrays, see A208510. %F A209576 u(n,x)=x*u(n-1,x)+v(n-1,x), %F A209576 v(n,x)=2x*u(n-1,x)+2x*v(n-1,x)+1, %F A209576 where u(1,x)=1, v(1,x)=1. %e A209576 First five rows: %e A209576 1 %e A209576 1...4 %e A209576 1...4...10 %e A209576 1...4...18...22 %e A209576 1...4...18...66...46 %e A209576 First three polynomials v(n,x): 1, 1+4x, 1+4x+10x^2. %t A209576 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209576 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x]; %t A209576 v[n_, x_] := 2 x*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A209576 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209576 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209576 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209576 TableForm[cu] %t A209576 Flatten[%] (* A209575 *) %t A209576 Table[Expand[v[n, x]], {n, 1, z}] %t A209576 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209576 TableForm[cv] %t A209576 Flatten[%] (* A209576 *) %Y A209576 Cf. A209575, A208510. %K A209576 nonn,tabl %O A209576 1,3 %A A209576 _Clark Kimberling_, Mar 11 2012