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 A210216 #5 Jul 12 2012 00:40:00 %S A210216 1,1,2,1,3,3,1,3,7,4,1,3,8,14,5,1,3,8,20,25,6,1,3,8,21,46,41,7,1,3,8, %T A210216 21,54,97,63,8,1,3,8,21,55,133,189,92,9,1,3,8,21,55,143,309,344,129, %U A210216 10,1,3,8,21,55,144,364,674,591,175,11,1,3,8,21,55,144,376,894 %N A210216 Triangle of coefficients of polynomials v(n,x) jointly generated with A210215; see the Formula section. %C A210216 Limiting row: even-indexed Fibonacci numbers, A001906. %C A210216 n-th row sum: -1+2*n %C A210216 For a discussion and guide to related arrays, see A208510. %F A210216 u(n,x)=x*u(n-1,x)+v(n-1,x)+1, %F A210216 v(n,x)=xu(n-1,x)+x*v(n-1,x)+1, %F A210216 where u(1,x)=1, v(1,x)=1. %e A210216 First five rows: %e A210216 1 %e A210216 1...2 %e A210216 1...3...3 %e A210216 1...3...7...4 %e A210216 1...3...8...14...5 %e A210216 First three polynomials v(n,x): 1, 1 + 2x , 1 + 3x + 3x^2. %t A210216 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210216 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x] + 1; %t A210216 v[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A210216 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210216 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210216 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210216 TableForm[cu] %t A210216 Flatten[%] (* A210215 *) %t A210216 Table[Expand[v[n, x]], {n, 1, z}] %t A210216 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210216 TableForm[cv] %t A210216 Flatten[%] (* A210216 *) %t A210216 Table[u[n, x] /. x -> 1, {n, 1, z}] (* A000225 *) %t A210216 Table[v[n, x] /. x -> 1, {n, 1, z}] (* A000225 *) %t A210216 Table[u[n, x] /. x -> -1, {n, 1, z}] (* A137470 *) %t A210216 Table[v[n, x] /. x -> -1, {n, 1, z}] (* A137470 *) %Y A210216 Cf. A210215, A208510. %K A210216 nonn,tabl %O A210216 1,3 %A A210216 _Clark Kimberling_, Mar 19 2012