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 A210549 #6 Mar 30 2012 18:58:16 %S A210549 1,1,2,1,3,4,1,3,9,8,1,3,10,25,16,1,3,10,33,65,32,1,3,10,34,104,161, %T A210549 64,1,3,10,34,115,311,385,128,1,3,10,34,116,381,886,897,256,1,3,10,34, %U A210549 116,395,1224,2421,2049,512,1,3,10,34,116,396,1334,3796,6388 %N A210549 Triangle of coefficients of polynomials u(n,x) jointly generated with A210550; see the Formula section. %C A210549 Each row begins with 1 and ends with 2^(n-1). %C A210549 Row sums: 1,3,8,21,..., the even-indexed Fibonacci numbers %C A210549 For a discussion and guide to related arrays, see A208510. %F A210549 u(n,x)=x*u(n-1,x)+x*v(n-1,x)+1, %F A210549 v(n,x)=u(n-1,x)+2x*v(n-1,x)+1, %F A210549 where u(1,x)=1, v(1,x)=1. %e A210549 First five rows: %e A210549 1 %e A210549 1...2 %e A210549 1...3...4 %e A210549 1...3...9....8 %e A210549 1...3...10...25...16 %e A210549 First three polynomials u(n,x): 1, 1 + 2x, 1 + 3x + 4x^2. %t A210549 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210549 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x] + 1; %t A210549 v[n_, x_] := (x + 1)*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A210549 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210549 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210549 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210549 TableForm[cu] %t A210549 Flatten[%] (* A210235 *) %t A210549 Table[Expand[v[n, x]], {n, 1, z}] %t A210549 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210549 TableForm[cv] %t A210549 Flatten[%] (* A210236 *) %Y A210549 Cf. A210550, A208510. %K A210549 nonn,tabl %O A210549 1,3 %A A210549 _Clark Kimberling_, Mar 22 2012