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 A208915 #5 Mar 30 2012 18:58:14 %S A208915 1,1,2,1,4,6,1,6,12,14,1,8,18,36,38,1,10,24,66,108,94,1,12,30,104,210, %T A208915 308,246,1,14,36,150,344,674,892,622,1,16,42,204,510,1224,2098,2500, %U A208915 1606,1,18,48,266,708,1990,4024,6402,7052,4094,1,20,54,336,938 %N A208915 Triangle of coefficients of polynomials u(n,x) jointly generated with A208916; see the Formula section. %C A208915 For a discussion and guide to related arrays, see A208510. %F A208915 u(n,x)=u(n-1,x)+2x*v(n-1,x), %F A208915 v(n,x)=2x*u(n-1,x)+x*v(n-1,x)+1, %F A208915 where u(1,x)=1, v(1,x)=1. %e A208915 First five rows: %e A208915 1 %e A208915 1...2 %e A208915 1...4...6 %e A208915 1...6...12...14 %e A208915 1...8...18...36...38 %e A208915 First five polynomials u(n,x): %e A208915 1 %e A208915 1 + 2x %e A208915 1 + 4x + 6x^2 %e A208915 1 + 6x + 12x^2 + 14x^3 %e A208915 1 + 8x + 18x^2 + 36x^3 + 38x^4 %t A208915 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A208915 u[n_, x_] := u[n - 1, x] + 2 x*v[n - 1, x]; %t A208915 v[n_, x_] := 2 x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A208915 Table[Expand[u[n, x]], {n, 1, z/2}] %t A208915 Table[Expand[v[n, x]], {n, 1, z/2}] %t A208915 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A208915 TableForm[cu] %t A208915 Flatten[%] (* A208915 *) %t A208915 Table[Expand[v[n, x]], {n, 1, z}] %t A208915 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A208915 TableForm[cv] %t A208915 Flatten[%] (* A208916 *) %Y A208915 Cf. A208914, A208510. %K A208915 nonn,tabl %O A208915 1,3 %A A208915 _Clark Kimberling_, Mar 03 2012