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 A209152 #5 Mar 30 2012 18:58:15 %S A209152 1,2,1,3,5,3,4,10,14,7,5,16,32,37,17,6,23,58,97,98,41,7,31,93,197,287, %T A209152 257,99,8,40,138,348,642,830,670,239,9,50,194,562,1234,2024,2360,1737, %U A209152 577,10,61,262,852,2148,4198,6220,6617,4482,1393,11,73,343 %N A209152 Triangle of coefficients of polynomials u(n,x) jointly generated with A208339; see the Formula section. %C A209152 Alternating row sums: 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,... %C A209152 For a discussion and guide to related arrays, see A208510. %F A209152 u(n,x)=u(n-1,x)+(x+1)*v(n-1,x), %F A209152 v(n,x)=x*u(n-1,x)+2x*v(n-1,x)+1, %F A209152 where u(1,x)=1, v(1,x)=1. %e A209152 First five rows: %e A209152 1 %e A209152 2...1 %e A209152 3...5....3 %e A209152 4...10...14...7 %e A209152 5...16...32...37...17 %e A209152 First three polynomials v(n,x): 1, 2 + x, 3 + 5x + 3x^2. %t A209152 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209152 u[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209152 v[n_, x_] := x*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A209152 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209152 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209152 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209152 TableForm[cu] %t A209152 Flatten[%] (* A209152 *) %t A209152 Table[Expand[v[n, x]], {n, 1, z}] %t A209152 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209152 TableForm[cv] %t A209152 Flatten[%] (* A208339 *) %Y A209152 Cf. A208339, A208510. %K A209152 nonn,tabl %O A209152 1,2 %A A209152 _Clark Kimberling_, Mar 07 2012