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 A209700 #5 Mar 30 2012 18:58:15 %S A209700 1,2,2,3,2,4,4,2,8,8,5,2,14,16,16,6,2,22,26,40,32,7,2,32,38,78,88,64, %T A209700 8,2,44,52,134,178,200,128,9,2,58,68,212,310,446,440,256,10,2,74,86, %U A209700 316,492,846,1042,968,512,11,2,92,106,450,732,1452,2062,2462 %N A209700 Triangle of coefficients of polynomials v(n,x) jointly generated with A209699; see the Formula section. %C A209700 For a discussion and guide to related arrays, see A208510. %F A209700 u(n,x)=x*u(n-1,x)+x*v(n-1,x), %F A209700 v(n,x)=2x*u(n-1,x)+v(n-1,x)+1, %F A209700 where u(1,x)=1, v(1,x)=1. %e A209700 First five rows: %e A209700 1 %e A209700 2...2 %e A209700 3...2...4 %e A209700 4...2...8....8 %e A209700 5...2...14...16...16 %e A209700 First three polynomials v(n,x): 1, 2 + 2x , 3 + 2x + 4x^2. %t A209700 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209700 u[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x]; %t A209700 v[n_, x_] := 2 x*u[n - 1, x] + v[n - 1, x] + 1; %t A209700 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209700 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209700 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209700 TableForm[cu] %t A209700 Flatten[%] (* A209699 *) %t A209700 Table[Expand[v[n, x]], {n, 1, z}] %t A209700 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209700 TableForm[cv] %t A209700 Flatten[%] (* A209700 *) %Y A209700 Cf. A209699, A208510. %K A209700 nonn,tabl %O A209700 1,2 %A A209700 _Clark Kimberling_, Mar 12 2012