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 A210227 #4 Mar 30 2012 18:58:16 %S A210227 1,2,1,2,6,1,2,8,16,1,2,8,32,38,1,2,8,36,112,84,1,2,8,36,156,348,178, %T A210227 1,2,8,36,164,620,988,368,1,2,8,36,164,732,2244,2624,750,1,2,8,36,164, %U A210227 748,3108,7468,6632,1516,1,2,8,36,164,748,3380,12348,23164 %N A210227 Triangle of coefficients of polynomials u(n,x) jointly generated with A210228; see the Formula section. %C A210227 For a discussion and guide to related arrays, see A208510. %F A210227 u(n,x)=x*u(n-1,x)+v(n-1,x)+1, %F A210227 v(n,x)=2x*u(n-1,x)+2x*v(n-1,x)+1, %F A210227 where u(1,x)=1, v(1,x)=1. %e A210227 First five rows: %e A210227 1 %e A210227 2...1 %e A210227 2...6...1 %e A210227 2...8...16...1 %e A210227 2...8...32...38...1 %e A210227 First three polynomials u(n,x): 1, 2 + x, 2 + 6x + x^2. %t A210227 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210227 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x] + 1; %t A210227 v[n_, x_] := 2 x*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A210227 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210227 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210227 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210227 TableForm[cu] %t A210227 Flatten[%] (* A210225 *) %t A210227 Table[Expand[v[n, x]], {n, 1, z}] %t A210227 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210227 TableForm[cv] %t A210227 Flatten[%] (* A210226 *) %Y A210227 Cf. A210228, A208510. %K A210227 nonn,tabl %O A210227 1,2 %A A210227 _Clark Kimberling_, Mar 20 2012