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 A209768 #5 Mar 30 2012 18:58:15 %S A209768 1,2,3,3,7,7,4,14,26,17,5,24,64,83,41,6,37,130,251,250,99,7,53,233, %T A209768 599,899,723,239,8,72,382,1232,2478,3022,2034,577,9,94,586,2282,5774, %U A209768 9476,9700,5607,1393,10,119,854,3908,11952,24734,34152,30063 %N A209768 Triangle of coefficients of polynomials v(n,x) jointly generated with A209767; see the Formula section. %C A209768 For a discussion and guide to related arrays, see A208510. %F A209768 u(n,x)=x*u(n-1,x)+(x+1)*v(n-1,x), %F A209768 v(n,x)=2x*u(n-1,x)+(x+1)*v(n-1,x)+1, %F A209768 where u(1,x)=1, v(1,x)=1. %e A209768 First five rows: %e A209768 1 %e A209768 2...3 %e A209768 3...7....7 %e A209768 4...14...26...17 %e A209768 5...24...64...83...41 %e A209768 First three polynomials v(n,x): 1, 2 + 3x , 3 + 7x + 7x^2. %t A209768 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209768 u[n_, x_] := x*u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209768 v[n_, x_] := 2 x*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A209768 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209768 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209768 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209768 TableForm[cu] %t A209768 Flatten[%] (* A209767 *) %t A209768 Table[Expand[v[n, x]], {n, 1, z}] %t A209768 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209768 TableForm[cv] %t A209768 Flatten[%] (* A209768 *) %Y A209768 Cf. A209667, A208510. %K A209768 nonn,tabl %O A209768 1,2 %A A209768 _Clark Kimberling_, Mar 15 2012