cp's OEIS Frontend

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.

A208328 Triangle of coefficients of polynomials u(n,x) jointly generated with A208329; see the Formula section.

Original entry on oeis.org

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

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Author

Clark Kimberling, Feb 26 2012

Keywords

Comments

Row sums, u(n,1): A000129
Row sums, v(n,1): A001333
Subtriangle of the triangle T(n,k) given by (1, 0, -1, 1, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (0, 1, 2, -2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - Philippe Deléham, Mar 07 2012

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

  • 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.
Sum_{k=0..n, n>0} T(n,k)*x^k = A000012(n), A000129(n), A083858(n) for x = 0, 1, 2 respectively. (End)