A008299 → D

nonnegative coefficients

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

Recurrence

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

\(P_{0}(x) = 0\)

\(P_{1}(x) = 0\)

\(P_{2}(x) = 3\)

\(P_{3}(x) = 10\)

Rows ?

n	x⁰	x¹	x²	P_n(1)
0				0
1				0
2	3			3
3	10			10
4	25	30		55
5	56	210		266
6	119	980	315	1414
7	246	3836	3780	7862

All 15 rows

Technical details

Node id: n-d03ddde5fd28759d · revision 0 · JSON
Definition source: derived:derivative
Fingerprint: f6-21a40980bc614967

Observed on the stored rows ?

Degrees: -1, -1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6 (half affine: slope 1, intercept -2)
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:    0;
  1:    0;
  2:    3;
  3:   10;
  4:   25,    30;
  5:   56,   210;
  6:  119,   980,    315;
  7:  246,  3836,   3780;
  8:  501, 13650,  28350,  3780;
  9: 1012, 45870, 170940, 69300;

%F Formula

The row polynomials satisfy n*P(n,x) = -(n^3-n)*x^2*P(n-4,x) - (2*n^2+2*n)*x*P(n-3,x) - (n^2+n)*x^2*d/dx P(n-3,x) - (2*n+2-(2*n^2+2*n)*x)*P(n-2,x) - (n+1)*x*d/dx P(n-2,x) + (3*n+1)*P(n-1,x) + n*x*d/dx P(n-1,x) for n >= 4, with P(0,x) = 0, P(1,x) = 0, P(2,x) = 3, P(3,x) = 10.

%t Mathematica

P[0, x_] := 0;
P[1, x_] := 0;
P[2, x_] := 3;
P[3, x_] := 10;
P[n_, x_] := P[n, x] = Expand[Together[(-(n^3 - n)*x^2*P[n - 4, x] - (2*n^2 + 2*n)*x*P[n - 3, x] - (n^2 + n)*x^2*D[P[n - 3, x], x] - (2*n + 2 - (2*n^2 + 2*n)*x)*P[n - 2, x] - (n + 1)*x*D[P[n - 2, x], x] + (3*n + 1)*P[n - 1, x] + n*x*D[P[n - 1, x], x])/(n)]];
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] = 0; v[3] = 3; v[4] = 10; for(n = 4, N, my(i = n + 1); v[i] = (-(n^3 - n)*x^2*v[i - 4] - (2*n^2 + 2*n)*x*v[i - 3] - (n^2 + n)*x^2*deriv(v[i - 3], x) - (2*n + 2 - (2*n^2 + 2*n)*x)*v[i - 2] - (n + 1)*x*deriv(v[i - 2], x) + (3*n + 1)*v[i - 1] + n*x*deriv(v[i - 1], x))/(n)); 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

Real-rooted? Every row P_n, n ≥ 0, is zero or real-rooted with all roots in (−∞, 0]
by Laguerre’s theorem on differential operators
Coefficients of one sign? Every nonzero row, n ≥ 0: the coefficients of P_n have one sign
derived from Laguerre’s theorem on differential operators
Hadamard kernel (Malo)? Rows P_n, n ≥ 0, are Hadamard kernels (preserve real-rootedness)
derived from Laguerre’s theorem on differential operators

Proof chains ? JSON

Laguerre’s theorem on differential operators [SP14] polytool ? step ›
- from Triangle T(n,k) of associated Stirling numbers of second kind, n >= 2, 1 <= k <= floor(n/2).?
  - Liu–Wang theorem for three-term recurrences [LW07, Thm 2.1, Thm 2.3, Cor 2.4, Prop 3.3] polytool ? step › direct check

References

[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
[SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.