A208328 Triangle of coefficients of polynomials u(n,x) jointly generated with A208329; see the Formula section.
1, 1, 1, 1, 1, 3, 1, 1, 5, 5, 1, 1, 7, 9, 11, 1, 1, 9, 13, 25, 21, 1, 1, 11, 17, 43, 53, 43, 1, 1, 13, 21, 65, 97, 125, 85, 1, 1, 15, 25, 91, 153, 255, 273, 171, 1, 1, 17, 29, 121, 221, 441, 597, 609, 341, 1, 1, 19, 33, 155, 301, 691, 1089, 1443, 1325, 683, 1, 1, 21
Offset: 1
Examples
First five rows: 1; 1, 1; 1, 1, 3; 1, 1, 5, 5; 1, 1, 7, 9, 11; First five polynomials u(n,x): 1 1 + x 1 + x + 3x^2 1 + x + 5x^2 + 5x^3 1 + x + 7x^2 + 9x^3 + 11x^4. From _Philippe Deléham_, Mar 07 2012: (Start) (1, 0, -1, 1, 0, 0, 0, ...) DELTA (0, 1, 2, -2, 0, 0, 0, ...) begins: 1; 1, 0; 1, 1, 0; 1, 1, 3, 0; 1, 1, 5, 5, 0; 1, 1, 7, 9, 11, 0; 1, 1, 9, 13, 25, 21, 0; 1, 1, 11, 17, 43, 53, 43, 0; (End)
Crossrefs
Cf. A208329.
Programs
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Mathematica
u[1, x_] := 1; v[1, x_] := 1; z = 13; u[n_, x_] := u[n - 1, x] + x*v[n - 1, x]; v[n_, x_] := 2 x*u[n - 1, x] + x*v[n - 1, x]; Table[Expand[u[n, x]], {n, 1, z/2}] Table[Expand[v[n, x]], {n, 1, z/2}] cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; TableForm[cu] Flatten[%] (* A208328 *) Table[Expand[v[n, x]], {n, 1, z}] cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; TableForm[cv] Flatten[%] (* A208329 *)
Formula
u(n,x) = u(n-1,x) + x*v(n-1,x),
v(n,x) = 2x*u(n-1,x) + x*v(n-1,x),
where u(1,x)=1, v(1,x)=1.
From Philippe Deléham, Mar 07 2012: (Start)
As DELTA-triangle T(n,k), 0 <= k <= n:
G.f.: (1-y*x - y*(2*y-1)*x^2)/(1-(1+y)*x-y(2*y-1)*x^2).
T(n,k) = T(n-1,k) + T(n-1,k-1) - T(n-2,k-1) + 2*T(n-2,k-2), T(0,0) = 1, T(1,0) = 1, T(1,1) = 0, T(n,k) = 0 if k < 0 or if k > n.
Comments