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.

A209171 Triangle of coefficients of polynomials v(n,x) jointly generated with A209170; see the Formula section.

Original entry on oeis.org

1, 3, 2, 6, 8, 3, 12, 25, 19, 5, 24, 68, 77, 40, 8, 48, 172, 259, 201, 80, 13, 96, 416, 782, 806, 478, 154, 21, 192, 976, 2200, 2825, 2222, 1067, 289, 34, 384, 2240, 5888, 9048, 8857, 5640, 2277, 532, 55, 768, 5056, 15184, 27160, 31787, 25184, 13483
Offset: 1

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Author

Clark Kimberling, Mar 08 2012

Keywords

Comments

Column 1: Fibonacci numbers (A000045).
Alternating row sums: 1,1,1,1,1,1,1,1,1,1,1,1,...
For a discussion and guide to related arrays, see A208510.
Subtriangle of (1, 2, -3/2, 1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (0, 2, -1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - Philippe Deléham, Mar 10 2012

Examples

			First five rows:
   1;
   3,  2;
   6,  8,  3;
  12, 25, 19,  5;
  24, 68, 77, 40,  8;
First three polynomials v(n,x):
  1
  3 + 2x
  6 + 8x + 3x^2.
From _Philippe Deléham_, Mar 10 2012: (Start)
Triangle (1, 2, -3/2, 1/2, 0, 0, ...) DELTA (0, 2, -1/2, -1/2, 0, 0, ...) begins (0 <= k <= n):
   1;
   1,   0;
   3,   2,   0;
   6,   8,   3,   0;
  12,  25,  19,   5,   0;
  24,  68,  77,  40,   8,   0;
  48, 172, 259, 201,  80,  13,   0;
  96, 416, 782, 806, 478, 154,  21,   0; (End)
		

Crossrefs

Programs

  • Mathematica
    u[1, x_] := 1; v[1, x_] := 1; z = 16;
    u[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x];
    v[n_, x_] := (x + 1)*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1;
    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[%]    (* A209170 *)
    Table[Expand[v[n, x]], {n, 1, z}]
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]    (* A209171 *)

Formula

u(n,x) = u(n-1,x) + (x+1)*v(n-1,x),
v(n,x) = (x+1)*u(n-1,x) + (x+1)*v(n-1,x)+1,
where u(1,x)=1, v(1,x)=1.
T(n,k) = 2*T(n-1,k) + T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2), T(1,0) = 1, T(2,0) = 3, T(2,1) = 2. - Philippe Deléham, Mar 10 2012
Sum_{k=0..n} T(n,k)*x^k = A000012(n), A003945(n-1), A007483(n-1) for x = -1, 0, 1 respectively. - Philippe Deléham, Mar 10 2012
G.f.: (-1-x-x*y)*x*y/(-1+2*x+x*y+x^2*y^2+x^2*y). - R. J. Mathar, Aug 12 2015