A122431 → reverse

palindromic γ-positive nonnegative coefficients only rational roots

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

Recurrence

\(P_{n}(x) = \left(1\right)\,P_{n-1}(x)\)

\(P_{0}(x) = 1 + 3\,x + 3\,x^{2} + x^{3}\)

Rows ?

n	x⁰	x¹	x²	x³	P_n(1)
0	1	3	3	1	8
1	1	3	3	1	8
2	1	3	3	1	8
3	1	3	3	1	8
4	1	3	3	1	8
5	1	3	3	1	8
6	1	3	3	1	8
7	1	3	3	1	8

Show all 15 stored rows

Computed in your browser ?

Technical details

Node id: n-1bc415e3a319469d · revision 1 · JSON
Definition source: derived:reversal
Fingerprint: f6-5659ab0d98136444

Observed on the stored rows ?

Degrees: 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 (affine: slope 0, intercept 3)
Palindromic rows: yes
γ-positive (gamma_positive): yes
Nonnegative coefficients (nonn): yes
Only rational roots (rr_by_factors: every nonzero row is a product of linear factors over ℚ): yes

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, 3, 3, 1;
  1: 1, 3, 3, 1;
  2: 1, 3, 3, 1;
  3: 1, 3, 3, 1;
  4: 1, 3, 3, 1;
  5: 1, 3, 3, 1;
  6: 1, 3, 3, 1;
  7: 1, 3, 3, 1;
  8: 1, 3, 3, 1;
  9: 1, 3, 3, 1;

%F Formula

The row polynomials satisfy P(n,x) = P(n-1,x) for n >= 1, with P(0,x) = 1 + 3*x + 3*x^2 + x^3.

%t Mathematica

P[0, x_] := 1 + 3*x + 3*x^2 + x^3;
P[n_, x_] := P[n, x] = Expand[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 + 3*x + 3*x^2 + x^3; for(n = 1, N, my(i = n + 1); v[i] = 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-d15d6831373644cf
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-d15d6831373644cf
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-d15d6831373644cf

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

preserver_image reversal, shift 0 e-d15d6831373644cf

Affine, reversal and Möbius substitutions (elementary) polytool ?
- premise (sequence): Riordan array ((1+x)^3,x).
  uses: Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, 0]
  - parent_provers periodic_product e-73f8c6c9e8d957af root: theorem check
    
    Parent-row provers of polytool polytool ?

Related sequences ?

Same fingerprint (1)

Equal up to content, sign, reversal and a small index shift.

Riordan array ((1+x)^3,x).