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.

A094442 Triangular array T(n,k) = Fibonacci(n+2-k)*C(n,k), 0 <= k <= n.

Original entry on oeis.org

1, 2, 1, 3, 4, 1, 5, 9, 6, 1, 8, 20, 18, 8, 1, 13, 40, 50, 30, 10, 1, 21, 78, 120, 100, 45, 12, 1, 34, 147, 273, 280, 175, 63, 14, 1, 55, 272, 588, 728, 560, 280, 84, 16, 1, 89, 495, 1224, 1764, 1638, 1008, 420, 108, 18, 1, 144, 890, 2475, 4080, 4410, 3276, 1680, 600, 135, 20, 1
Offset: 0

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Author

Clark Kimberling, May 03 2004

Keywords

Comments

Triangle of coefficients of polynomials v(n,x) jointly generated with A094441; see the Formula section.
Column 1: Fibonacci numbers, A000045
Row sums: even-indexed Fibonacci numbers
Alternating row sum: signed Fibonacci numbers
For a discussion and guide to related arrays, see A208510.
Subtriangle of the triangle given by (0, 2, -1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - Philippe Deléham, Apr 02 2012

Examples

			First five rows:
  1;
  2,  1;
  3,  4,  1;
  5,  9,  6, 1;
  8, 20, 18, 8, 1;
First three polynomials v(n,x): 1, 2 + x, 3 + 4x + x^2.
From _Philippe Deléham_, Apr 02 2012: (Start)
(0, 2, -1/2, -1/2, 0, 0, 0, ...) DELTA (1, 0, 0, 1, 0, 0, ...) begins:
  1;
  0, 1;
  0, 2,  1;
  0, 3,  4,  1;
  0, 5,  9,  6, 1;
  0, 8, 20, 18, 8, 1. (End)
		

Crossrefs

Programs

  • GAP
    Flat(List([0..12], n-> List([0..n], k-> Binomial(n,k)*Fibonacci(n-k+2) ))); # G. C. Greubel, Oct 30 2019
  • Magma
    [Binomial(n,k)*Fibonacci(n-k+2): k in [0..n], n in [0..12]]; // G. C. Greubel, Oct 30 2019
    
  • Maple
    with(combinat); seq(seq(fibonacci(n-k+2)*binomial(n,k), k=0..n), n=0..12); # G. C. Greubel, Oct 30 2019
  • Mathematica
    (* First program *)
    u[1, x_] := 1; v[1, x_] := 1; z = 16;
    u[n_, x_] := x*u[n - 1, x] + v[n - 1, x];
    v[n_, x_] := u[n - 1, x] + (x + 1)*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[%]    (* A094441 *)
    Table[Expand[v[n, x]], {n, 1, z}]
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]    (* A094442 *)
    (* Second program *)
    Table[Fibonacci[n-k+2]*Binomial[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Oct 30 2019 *)
  • PARI
    T(n,k) = binomial(n,k)*fibonacci(n-k+2);
    for(n=0,12, for(k=0,n, print1(T(n,k), ", "))) \\ G. C. Greubel, Oct 30 2019
    
  • Sage
    [[binomial(n,k)*fibonacci(n-k+2) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Oct 30 2019
    

Formula

Let u(n,x) = x*u(n-1,x) + v(n-1,x) and v(n,x) = u(n-1,x) + (x+1)*v(n-1, x), where u(1,x)=1, v(1,x)=1 then the coefficients of the polynomials of v(n,x) produce this sequence.
T(n,k) = T(n-1, k) + 2*T(n-1,k-1) + T(n-2,k) - T(n-2,k-1) - T(n-2,k-2), T(1,0) = T(2,1) = 1, T(2,0) = 2 and T(n,k) = 0 if k < 0 or if k >= n. - Philippe Deléham, Apr 02 2012
From G. C. Greubel, Oct 30 2019: (Start)
T(n,k) = binomial(n,k)*Fibonacci(n-k+2).
Sum_{k=0..n} T(n,k) = Fibonacci(2*n+2)
Sum_{k=0..n} (-1)^(k+1) * T(n,k) = (-1)^n * Fibonacci(n-2). (End)