A124860 → D

palindromicγ-positivenonnegative coefficientsonly rational roots

Proved for all n all roots real, in (−∞, 0]coefficients of one signHadamard kernel

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13Pn(1)
00
111
26612
315301560
44413213244352
51054206304201051680
625812902580258012902588256
759535708925119008925357059538080
8136895762872847880478802872895761368175104
93069245528593217186421483017186485932245523069785664
106830614702458805737208605808605805737202458806147068303496960
1115015150150675675180180031531503783780315315018018006756751501501501515375360
12327723604921802460540738010814760151406641514066410814760540738018024603604923277267117056
1370993851916468553815618460351415355622645665597532562264563514153515618460468553885191670993290787328
1415292219879861192791643735692109339230196810614262414152262414152196810614109339230437356921192791619879861529221252737024
Technical details
Node id
n-e561d011b1cd2c01 · revision 0 · JSON
Definition source
derived:derivative
Fingerprint
f6-77a7ed3b1d5f257e

Observed on the stored rows ?

  • Degrees: -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 (affine: slope 1, intercept -1)
  • 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

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 0, …, ascending powers of x
%e Example
Triangle begins:
  0:    0;
  1:    1;
  2:    6,     6;
  3:   15,    30,    15;
  4:   44,   132,   132,     44;
  5:  105,   420,   630,    420,    105;
  6:  258,  1290,  2580,   2580,   1290,    258;
  7:  595,  3570,  8925,  11900,   8925,   3570,   595;
  8: 1368,  9576, 28728,  47880,  47880,  28728,  9576,  1368;
  9: 3069, 24552, 85932, 171864, 214830, 171864, 85932, 24552, 3069;
%F Formula
The row polynomials satisfy (n^2-3*n+2)*P(n,x) = (2*n^2-2*n+(4*n^2-4*n)*x+(2*n^2-2*n)*x^2)*P(n-2,x) + (n^2-2*n+(n^2-2*n)*x)*P(n-1,x) for n >= 3, with P(0,x) = 0, P(1,x) = 1, P(2,x) = 6 + 6*x.
%t Mathematica
P[0, x_] := 0;
P[1, x_] := 1;
P[2, x_] := 6 + 6*x;
P[n_, x_] := P[n, x] = Expand[Together[((2*n^2 - 2*n + (4*n^2 - 4*n)*x + (2*n^2 - 2*n)*x^2)*P[n - 2, x] + (n^2 - 2*n + (n^2 - 2*n)*x)*P[n - 1, x])/(n^2 - 3*n + 2)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N + 1)); v[1] = 0; v[2] = 1; v[3] = 6 + 6*x; for(n = 3, N, my(i = n + 1); v[i] = ((2*n^2 - 2*n + (4*n^2 - 4*n)*x + (2*n^2 - 2*n)*x^2)*v[i - 2] + (n^2 - 2*n + (n^2 - 2*n)*x)*v[i - 1])/(n^2 - 3*n + 2)); 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)

polytool c48629374597

Properties

Proof chains ? JSON

Same fingerprint ?

References

  1. [Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
  2. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.