A091917 Coefficient array of polynomials (z-1)^n-1.

1, -2, 1, 0, -2, 1, -2, 3, -3, 1, 0, -4, 6, -4, 1, -2, 5, -10, 10, -5, 1, 0, -6, 15, -20, 15, -6, 1, -2, 7, -21, 35, -35, 21, -7, 1, 0, -8, 28, -56, 70, -56, 28, -8, 1, -2, 9, -36, 84, -126, 126, -84, 36, -9, 1, 0, -10, 45, -120, 210, -252, 210, -120, 45, -10, 1, -2, 11, -55, 165, -330, 462, -462, 330, -165, 55, -11, 1

Offset

0,2

Comments

The first element has been changed to 1 to produce an invertible matrix. Alternatively, this is the coefficient array for the polynomials P(z,n) = Product_{j=0..n-1} (z-(1+w(n)^j)) where w(n) = e^(2*Pi*i/n), i=sqrt(-1).

The row entries determine interesting recurrences. For instance, a(n) = 4a(n-1) + 6a(n-2) + 4a(n-3), a(0)=a(1)=a(2)=1, gives A038503. Sequences of the form a(n) = Sum_{k=0..n} (binomial(n,k) if k mod m = r, otherwise 0), for r=0..m-1, result. Equivalently, a(n) = Sum_{j=0..n-1} 2^n*(cos(Pi*j/m))^n*cos((n-2r)Pi*j/m)/m, r=0..m-1. These include A024493, A024494, A024495, A038503, A038504, A038505. The inverse matrix is A091918.

Triangle T(n,k), 0 <= k <= n, read by rows given by [ -2, 2, 1/2, -1/2, 0, 0, 0, 0, 0, ...] DELTA [1, 0, -1/2, 1/2, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 11 2007

Links

Alois P. Heinz, Rows n = 0..140, flattened

Formula

T(n,k) = T(n-1,k-1) + T(n-2,k) - T(n-2,k-1), T(0,0) = T(1,1) = T(2,2) = 1, T(1,0) = T(2,1) = -2, T(2,0) = 0, T(n,k) = 0 for k > n or for k < 0. - Philippe Deléham, May 23 2015

G.f.: (1-2*x-x^2+x^2*y)/((x-1)*(-x+x*y-1)). - R. J. Mathar, Aug 11 2015

Example

Rows begin:
  { 1},
  {-2,  1},
  { 0, -2,  1},
  {-2,  3, -3,  1},
  { 0, -4,  6, -4,  1},
  ...

Maple

T:= n-> `if`(n=0, 1, (p-> seq(coeff(p, z, i), i=0..n))((z-1)^n-1)):
seq(T(n), n=0..12);  # Alois P. Heinz, May 23 2015

Mathematica

Table[If[n == 0, 1, CoefficientList[(z-1)^n-1, z]], {n, 0, 12}] // Flatten (* Jean-François Alcover, Apr 08 2016 *)

Prog

(PARI) row(n) = if (n==0, 1, Vecrev((z-1)^n-1)); \\ Michel Marcus, May 23 2015

Crossrefs

Sequence in context: A246369 A036261 A140575 * A025657 A025686 A215345

Adjacent sequences: A091914 A091915 A091916 * A091918 A091919 A091920

Keyword

sign,tabl

Author

Paul Barry, Feb 13 2004

Status

approved