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 A208916 #5 Mar 30 2012 18:58:14 %S A208916 1,1,3,1,3,7,1,3,11,19,1,3,15,35,47,1,3,19,51,107,123,1,3,23,67,183, %T A208916 323,311,1,3,27,83,275,603,939,803,1,3,31,99,383,963,1951,2723,2047,1, %U A208916 3,35,115,507,1403,3411,6147,7723,5259,1,3,39,131,647,1923,5383 %N A208916 Triangle of coefficients of polynomials v(n,x) jointly generated with A208915; see the Formula section. %C A208916 For a discussion and guide to related arrays, see A208510. %F A208916 u(n,x)=u(n-1,x)+2x*v(n-1,x), %F A208916 v(n,x)=2x*u(n-1,x)+x*v(n-1,x)+1, %F A208916 where u(1,x)=1, v(1,x)=1. %e A208916 First five rows: %e A208916 1 %e A208916 1...3 %e A208916 1...3...7 %e A208916 1...3...11...19 %e A208916 1...3...15...35...47 %e A208916 First five polynomials v(n,x): %e A208916 1 %e A208916 1 + 3x %e A208916 1 + 3x + 7x^2 %e A208916 1 + 3x + 11x^2 + 19x^3 %e A208916 1 + 3x + 15x^2 + 35x^3 + 47x^4 %t A208916 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A208916 u[n_, x_] := u[n - 1, x] + 2 x*v[n - 1, x]; %t A208916 v[n_, x_] := 2 x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A208916 Table[Expand[u[n, x]], {n, 1, z/2}] %t A208916 Table[Expand[v[n, x]], {n, 1, z/2}] %t A208916 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A208916 TableForm[cu] %t A208916 Flatten[%] (* A208915 *) %t A208916 Table[Expand[v[n, x]], {n, 1, z}] %t A208916 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A208916 TableForm[cv] %t A208916 Flatten[%] (* A208916 *) %Y A208916 Cf. A208915, A208510. %K A208916 nonn,tabl %O A208916 1,3 %A A208916 _Clark Kimberling_, Mar 03 2012