Real-rooted atlas

A081580 → γ → θ+1

nonnegative coefficients

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

Recurrence

\(\left(n + 5\,n^{2} x\right)\,P_{n}(x) = \left(-20\,x - 100\,x^{2} + n + 20\,n x + 50\,n x^{2} + 5\,n^{2} x + 50\,n^{2} x^{2}\right)\,P_{n-1}(x) + \left(-x - 30\,x^{2} - 200\,x^{3} - 5\,n x^{2} - 100\,n x^{3}\right)\,P_{n-1}'(x)\)
\(P_{0}(x) = 1\)

Rows ?

nx0x1x2x3Pn(1)
011
111
211011
312021
413075106
5140225266
61504505001001
716075020002811

All 15 rows

Technical details
Node id
n-ca421430671b74f1 · revision 0 · JSON
Definition source
derived:theta_plus_one
Fingerprint
f6-906b16ea0bf6fa73

Observed on the stored rows ?

  • Degrees: 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7 (half affine: slope 1, intercept 0)
  • 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

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 0, …, ascending powers of x
%e Example
Triangle begins:
  0: 1;
  1: 1;
  2: 1, 10;
  3: 1, 20;
  4: 1, 30,   75;
  5: 1, 40,  225;
  6: 1, 50,  450,   500;
  7: 1, 60,  750,  2000;
  8: 1, 70, 1125,  5000,  3125;
  9: 1, 80, 1575, 10000, 15625;
%F Formula
The row polynomials satisfy (n+5*n^2*x)*P(n,x) = (n+(5*n^2+20*n-20)*x+(50*n^2+50*n-100)*x^2)*P(n-1,x) - (x+(5*n+30)*x^2+(100*n+200)*x^3)*d/dx P(n-1,x) for n >= 1, with P(0,x) = 1.
%t Mathematica
P[0, x_] := 1;
P[n_, x_] := P[n, x] = Expand[Together[((n + (5*n^2 + 20*n - 20)*x + (50*n^2 + 50*n - 100)*x^2)*P[n - 1, x] - (x + (5*n + 30)*x^2 + (100*n + 200)*x^3)*D[P[n - 1, x], x])/(n + 5*n^2*x)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N + 1)); v[1] = 1; for(n = 1, N, my(i = n + 1); v[i] = ((n + (5*n^2 + 20*n - 20)*x + (50*n^2 + 50*n - 100)*x^2)*v[i - 1] - (x + (5*n + 30)*x^2 + (100*n + 200)*x^3)*deriv(v[i - 1], x))/(n + 5*n^2*x)); 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

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. [LW07] Lily L. Liu and Yi Wang. A unified approach to polynomial sequences with only real zeros. Advances in Applied Mathematics, 38(4):542–560, May 2007. doi:10.1016/j.aam.2006.02.003
  3. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.