Real-rooted atlas

A118933 → basis A008277

nonnegative coefficients

Proved for all n: all roots real, in (−∞, 0] · coefficients of one sign · Hadamard kernel what this means

Recurrence
\(P_{n}(x) = \left(-6 - 6\,x + 11\,n + 11\,n x - 6\,n^{2} - 6\,n^{2} x + n^{3} + n^{3} x\right)\,P_{n-4}(x) + \left(-6\,x + 11\,n x - 6\,n^{2} x + n^{3} x\right)\,P_{n-4}'(x) + \left(1\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 1\)
\(P_{1}(x) = 1\)
\(P_{2}(x) = 1\)
\(P_{3}(x) = 1\)

Rows ?

nx0x1Pn(1)
011
111
211
311
47613
5313061
69190181
7211210421

Show all 15 stored rows

Computed in your browser ?

Technical details
Node id
n-ff283d31b1efde95 · revision 1 · JSON
Definition source
derived:basis_map_A008277
Fingerprint
f6-f60f31b5a675bca5

Observed on the stored rows ?

  • Degrees: 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3 (irregular)
  • Palindromic rows: no
  • γ-positive (gamma_positive): no
  • Nonnegative coefficients (nonn): yes
  • Only rational roots (rr_by_factors: every nonzero row is a product of linear factors over ℚ): no

OEIS matches ?

No OEIS matches.

OEIS submission text ?

Fields to paste into an OEIS submission: the example %e, the formula %F and programs %t (Mathematica) and %o (PARI/GP) that list the same rows. For an OEIS link the row numbers, the offset and the orientation are those of the entry, as matched; the matched terms were compared with the published ones, which identifies the node with the entry on a finite prefix, not for every n. The PARI/GP program is not machine-checked here.

The atlas's own rows: n = 0, …, ascending powers of x
%e Example
Triangle begins:
  0:     1;
  1:     1;
  2:     1;
  3:     1;
  4:     7,     6;
  5:    31,    30;
  6:    91,    90;
  7:   211,   210;
  8:  1681,  4200,  1260;
  9: 12097, 34776, 11340;
%F Formula
The row polynomials satisfy P(n,x) = (n^3-6*n^2+11*n-6+(n^3-6*n^2+11*n-6)*x)*P(n-4,x) + (n^3-6*n^2+11*n-6)*x*d/dx P(n-4,x) + P(n-1,x) for n >= 4, with P(0,x) = 1, P(1,x) = 1, P(2,x) = 1, P(3,x) = 1.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 1;
P[2, x_] := 1;
P[3, x_] := 1;
P[n_, x_] := P[n, x] = Expand[(n^3 - 6*n^2 + 11*n - 6 + (n^3 - 6*n^2 + 11*n - 6)*x)*P[n - 4, x] + (n^3 - 6*n^2 + 11*n - 6)*x*D[P[n - 4, x], x] + P[n - 1, x]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N + 1)); v[1] = 1; v[2] = 1; v[3] = 1; v[4] = 1; for(n = 4, N, my(i = n + 1); v[i] = (n^3 - 6*n^2 + 11*n - 6 + (n^3 - 6*n^2 + 11*n - 6)*x)*v[i - 4] + (n^3 - 6*n^2 + 11*n - 6)*x*deriv(v[i - 4], x) + v[i - 1]); v};
row(n, p) = {my(c = Vecrev(p)); c};
T(N) = {my(v = P(N)); concat(vector(#v, i, row(i - 1, v[i])))};
T(9)

Generated with polytool c48629374597.

Proved properties

  • Real-rooted. Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, 0]
    Every polynomial of the sequence has only real roots, inside the stated interval.
    by the cited steps: e-510f97d2d65daac7
  • Coefficients of one sign. Every nonzero row, n >= 0: the coefficients of P_n have one sign
    All coefficients of each polynomial have the same sign (after x -> -x when alternating).
    derived from the cited steps by a stated theorem: e-510f97d2d65daac7
  • Hadamard kernel (Malo). Rows P_n, n >= 0, are Hadamard kernels (preserve real-rootedness)
    Multiplying the coefficients of any real-rooted polynomial termwise by those of a row (Hadamard product) gives a real-rooted polynomial again.
    derived from the cited steps by a stated theorem: e-510f97d2d65daac7

Proof chains

1 incoming proof step. Each step is expanded back to the roots of the proof DAG, the theorem checks of a node's own rule. JSON

No candidate equalities or related sequences.

References

  1. [MW08] Shi-Mei Ma and Yi Wang. q-Eulerian polynomials and polynomials with only real zeros. The Electronic Journal of Combinatorics, 15(1):Research Paper 17, January 2008. doi:10.37236/741