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 A208523 #5 Mar 30 2012 18:58:13 %S A208523 1,1,3,1,3,5,1,3,7,11,1,3,9,19,21,1,3,11,27,43,43,1,3,13,35,69,103,85, %T A208523 1,3,15,43,99,183,231,171,1,3,17,51,133,283,449,523,341,1,3,19,59,171, %U A208523 403,747,1107,1155,683,1,3,21,67,213,543,1133,1971,2637,2543 %N A208523 Triangle of coefficients of polynomials v(n,x) jointly generated with A208522; see the Formula section. %F A208523 u(n,x)=u(n-1,x)+x*v(n-1,x), %F A208523 v(n,x)=2x*u(n-1,x)+x*v(n-1,x)+1, %F A208523 where u(1,x)=1, v(1,x)=1. %e A208523 First five rows: %e A208523 1 %e A208523 1...3 %e A208523 1...3...5 %e A208523 1...3...7...11 %e A208523 1...3...9...19...21 %e A208523 First five polynomials v(n,x): %e A208523 1 %e A208523 1 + 3x %e A208523 1 + 3x + 5x^2 %e A208523 1 + 3x + 7x^2 + 11x^3 %e A208523 1 + 3x + 9x^2 + 19x^3 + 21x^4 %t A208523 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A208523 u[n_, x_] := u[n - 1, x] + x*v[n - 1, x]; %t A208523 v[n_, x_] := 2 x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A208523 Table[Expand[u[n, x]], {n, 1, z/2}] %t A208523 Table[Expand[v[n, x]], {n, 1, z/2}] %t A208523 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A208523 TableForm[cu] %t A208523 Flatten[%] (* A208522 *) %t A208523 Table[Expand[v[n, x]], {n, 1, z}] %t A208523 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A208523 TableForm[cv] %t A208523 Flatten[%] (* A208523 *) %Y A208523 Cf. A208522. %K A208523 nonn,tabl %O A208523 1,3 %A A208523 _Clark Kimberling_, Feb 29 2012