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 A209136 #13 Jan 24 2020 03:25:25 %S A209136 1,1,3,1,8,5,1,15,23,11,1,24,66,66,21,1,35,150,240,165,43,1,48,295, %T A209136 678,747,404,85,1,63,525,1631,2547,2157,947,171,1,80,868,3500,7246, %U A209136 8560,5864,2182,341,1,99,1356,6888,18126,28018,26592,15318,4929,683 %N A209136 Triangle of coefficients of polynomials v(n,x) jointly generated with A209135; see the Formula section. %C A209136 Alternating row sums: 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,... %C A209136 For a discussion and guide to related arrays, see A208510. %C A209136 Subtriangle of the triangle given by (1, 0, 2/3, 1/3, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (0, 3, -4/3, -2/3, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - _Philippe Deléham_, Apr 11 2012 %F A209136 u(n,x) = u(n-1,x) + (x+1)*v(n-1,x), %F A209136 v(n,x) = 2x*u(n-1,x) + (x+1)*v(n-1,x), %F A209136 where u(1,x)=1, v(1,x)=1. %F A209136 From _Philippe Deléham_, Apr 11 2012: (Start) %F A209136 As DELTA-triangle T(n,k) with 0 <= k <= n: %F A209136 G.f.: (1-x-y*x+y*x^2-2*y^2*x^2)/(1-2*x-y*x+x^2-y*x^2-2*y^2*x^2). %F A209136 T(n,k) = 2*T(n-1,k) + T(n-1,k-1) - T(n-2,k) + T(n-2,k-1) + 2*T(n-2,k-2), T(0,0) = T(1,0) = T(2,0) = 1, T(2,1) = 3, T(1,1) = T(2,2) = 0 and T(n,k) = 0 if k < 0 or if k > n. (End) %e A209136 First five rows: %e A209136 1; %e A209136 1, 3; %e A209136 1, 8, 5; %e A209136 1, 15, 23, 11; %e A209136 1, 24, 66, 66, 21; %e A209136 First three polynomials v(n,x): %e A209136 1 %e A209136 1 + 3x %e A209136 1 + 8x + 5x^2. %e A209136 From _Philippe Deléham_, Apr 11 2012: (Start) %e A209136 (1, 0, 2/3, 1/3, 0, 0, 0, ...) DELTA (0, 3, -4/3, -2/3, 0, 0, 0, ...) begins: %e A209136 1; %e A209136 1, 0; %e A209136 1, 3, 0; %e A209136 1, 8, 5, 0; %e A209136 1, 15, 23, 11, 0; %e A209136 1, 24, 66, 66, 21, 0; %e A209136 1, 35, 150, 240, 165, 43, 0; (End) %t A209136 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209136 u[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209136 v[n_, x_] := 2 x*u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209136 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209136 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209136 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209136 TableForm[cu] %t A209136 Flatten[%] (* A209135 *) %t A209136 Table[Expand[v[n, x]], {n, 1, z}] %t A209136 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209136 TableForm[cv] %t A209136 Flatten[%] (* A209136 *) %Y A209136 Cf. A209135, A208510. %K A209136 nonn,tabl %O A209136 1,3 %A A209136 _Clark Kimberling_, Mar 05 2012