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 A210233 #4 Mar 30 2012 18:58:16 %S A210233 1,2,1,3,5,1,4,10,12,1,5,18,30,27,1,6,27,68,83,58,1,7,39,119,225,217, %T A210233 121,1,8,52,200,454,680,544,248,1,9,68,300,866,1566,1928,1320,503,1, %U A210233 10,85,440,1450,3332,5014,5216,3121,1014,1,11,105,605,2350,6182 %N A210233 Triangle of coefficients of polynomials u(n,x) jointly generated with A210234; see the Formula section. %C A210233 For a discussion and guide to related arrays, see A208510. %F A210233 u(n,x)=x*u(n-1,x)+v(n-1,x)+1, %F A210233 v(n,x)=(x+1)*u(n-1,x)+2x*v(n-1,x)+1, %F A210233 where u(1,x)=1, v(1,x)=1. %e A210233 First five rows: %e A210233 1 %e A210233 2...1 %e A210233 3...5....1 %e A210233 4...10...12...1 %e A210233 5...18...30...27...1 %e A210233 First three polynomials u(n,x): 1, 2 + x, 3 + 5x + x^2. %t A210233 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210233 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x] + 1; %t A210233 v[n_, x_] := (x + 1)*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A210233 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210233 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210233 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210233 TableForm[cu] %t A210233 Flatten[%] (* A210233 *) %t A210233 Table[Expand[v[n, x]], {n, 1, z}] %t A210233 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210233 TableForm[cv] %t A210233 Flatten[%] (* A210234 *) %Y A210233 Cf. A210234, A208510. %K A210233 nonn,tabl %O A210233 1,2 %A A210233 _Clark Kimberling_, Mar 20 2012