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 A210873 #6 Oct 02 2013 16:26:12 %S A210873 1,1,2,1,1,3,1,1,3,4,1,1,2,8,5,1,1,2,6,17,6,1,1,2,5,18,31,7,1,1,2,5, %T A210873 14,47,51,8,1,1,2,5,13,41,107,78,9,1,1,2,5,13,35,115,218,113,10,1,1,2, %U A210873 5,13,34,98,296,407,157,11,1,1,2,5,13,34,90,276,695,709,211,12 %N A210873 Triangle of coefficients of polynomials u(n,x) jointly generated with A210873; see the Formula section. %C A210873 Column 1: 1,1,1,1,1,1,1,1,1... %C A210873 Row sums: A083318 (1+2^n) %C A210873 Alternating row sums: A137470 %C A210873 Limiting row: 1,1,2,5,13,34,..., odd-indexed Fibonacci numbers %C A210873 If the term in row n and column k is written as U(n,k), then U(n,n-1)=A105163. %C A210873 For a discussion and guide to related arrays, see A208510. %F A210873 For a discussion and guide to related arrays, see A208510. %F A210873 u(n,x)=x*u(n-1,x)+v(n-1,x)-1, %F A210873 v(n,x)=x*u(n-1,x)+x*v(n-1,x)+1, %F A210873 where u(1,x)=1, v(1,x)=1. %e A210873 First six rows: %e A210873 1 %e A210873 1...2 %e A210873 1...1...3 %e A210873 1...1...3....4 %e A210873 1...1...2....8...5 %e A210873 1...1...2....6...17...6 %e A210873 First three polynomials v(n,x): 1, 1 + 2x, 1 + x + 3x^2 %t A210873 u[1, x_] := 1; v[1, x_] := 1; z = 14; %t A210873 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x] - 1; %t A210873 v[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A210873 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210873 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210873 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210873 TableForm[cu] %t A210873 Flatten[%] (* A210872 *) %t A210873 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210873 TableForm[cv] %t A210873 Flatten[%] (* A210873 *) %t A210873 Table[u[n, x] /. x -> 1, {n, 1, z}] (* A000225 *) %t A210873 Table[v[n, x] /. x -> 1, {n, 1, z}] (* A083318 *) %t A210873 Table[u[n, x] /. x -> -1, {n, 1, z}] (* -A077973 *) %t A210873 Table[v[n, x] /. x -> -1, {n, 1, z}] (* A137470 *) %Y A210873 Cf. A210872, A208510. %K A210873 nonn,tabl %O A210873 1,3 %A A210873 _Clark Kimberling_, Mar 29 2012