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 A210189 #4 Mar 30 2012 18:58:16 %S A210189 1,3,6,2,10,10,15,30,4,21,70,28,28,140,112,8,36,252,336,72,45,420,840, %T A210189 360,16,55,660,1848,1320,176,66,990,3696,3960,1056,32,78,1430,6864, %U A210189 10296,4576,416,91,2002,12012,24024,16016,2912,64,105,2730,20020 %N A210189 Triangle of coefficients of polynomials u(n,x) jointly generated with A210190; see the Formula section. %C A210189 Column 1: triangular numbers: A000217 %C A210189 For a discussion and guide to related arrays, see A208510. %F A210189 u(n,x)=u(n-1,x)+v(n-1,x)+1, %F A210189 v(n,x)=2x*u(n-1,x)+v(n-1,x)+1, %F A210189 where u(1,x)=1, v(1,x)=1. %e A210189 First five rows: %e A210189 1 %e A210189 3 %e A210189 6....2 %e A210189 10...10 %e A210189 15...30...4 %e A210189 First three polynomials u(n,x): 1, 3, 6 + 2x. %t A210189 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210189 u[n_, x_] := u[n - 1, x] + v[n - 1, x] + 1; %t A210189 v[n_, x_] := 2 x*u[n - 1, x] + v[n - 1, x] + 1; %t A210189 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210189 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210189 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210189 TableForm[cu] %t A210189 Flatten[%] (* A210189 *) %t A210189 Table[Expand[v[n, x]], {n, 1, z}] %t A210189 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210189 TableForm[cv] %t A210189 Flatten[%] (* A210190 *) %Y A210189 Cf. A210190, A208510. %K A210189 nonn,tabf %O A210189 1,2 %A A210189 _Clark Kimberling_, Mar 18 2012