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 A208930 #6 Mar 30 2012 18:58:14 %S A208930 1,2,3,2,7,8,2,11,26,22,2,15,52,88,60,2,19,86,214,288,164,2,23,128, %T A208930 416,820,916,448,2,27,178,710,1824,2984,2856,1224,2,31,236,1112,3500, %U A208930 7464,10464,8768,3344,2,35,302,1638,6080,15884,29040,35664,26592 %N A208930 Triangle of coefficients of polynomials v(n,x) jointly generated with A208930; see the Formula section. %C A208930 For a discussion and guide to related arrays, see A208510. %F A208930 u(n,x)=u(n-1,x)+2x*v(n-1,x), %F A208930 v(n,x)=(x+1)*u(n-1,x)+2x*v(n-1,x)+1, %F A208930 where u(1,x)=1, v(1,x)=1. %e A208930 First five rows: %e A208930 1 %e A208930 2...3 %e A208930 2...7....8 %e A208930 2...11...26...22 %e A208930 2...15...52...88...60 %e A208930 First five polynomials v(n,x): %e A208930 1 %e A208930 2 + 3x %e A208930 2 + 7x + 8x^2 %e A208930 2 + 11x + 26x^2 + 22x^3 %e A208930 2 + 15x + 52x^2 + 88x^3 + 60x^4 %t A208930 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A208930 u[n_, x_] := u[n - 1, x] + 2 x*v[n - 1, x]; %t A208930 v[n_, x_] := (x + 1)*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A208930 Table[Expand[u[n, x]], {n, 1, z/2}] %t A208930 Table[Expand[v[n, x]], {n, 1, z/2}] %t A208930 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A208930 TableForm[cu] %t A208930 Flatten[%] (* A208909 *) %t A208930 Table[Expand[v[n, x]], {n, 1, z}] %t A208930 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A208930 TableForm[cv] %t A208930 Flatten[%] (* A208930 *) %Y A208930 Cf. A208909, A208510. %K A208930 nonn,tabl %O A208930 1,2 %A A208930 _Clark Kimberling_, Mar 04 2012