Real-rooted atlas

A048993 → θ+1 → D

nonnegative coefficients

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6Pn(1)
00
122
2268
32181232
42427220136
529030020030622
6218610801300450423060
723783612700042008825616130

All 15 rows

Technical details
Node id
n-bc3430a0f257243c · revision 0 · JSON
Definition source
derived:derivative
Fingerprint
f6-df87a7a77830807f

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: 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: 2;
  2: 2,    6;
  3: 2,   18,    12;
  4: 2,   42,    72,     20;
  5: 2,   90,   300,    200,     30;
  6: 2,  186,  1080,   1300,    450,     42;
  7: 2,  378,  3612,   7000,   4200,    882,    56;
  8: 2,  762, 11592,  34020,  31500,  11172,  1568,   72;
  9: 2, 1530, 36300, 155400, 208530, 111132, 25872, 2592, 90;
%F Formula
The row polynomials satisfy P(n,x) = (3*x-6*x^2+x^3)*P(n-3,x) + (2*x-3*x^2)*d/dx P(n-3,x) + (x^2-x^3)*d^2/dx^2 P(n-3,x) + (1+6*x-3*x^2)*P(n-2,x) + 2*x*d/dx P(n-2,x) + x^2*d^2/dx^2 P(n-2,x) + 3*x*P(n-1,x) for n >= 3, with P(0,x) = 0, P(1,x) = 2, P(2,x) = 2 + 6*x.
%t Mathematica
P[0, x_] := 0;
P[1, x_] := 2;
P[2, x_] := 2 + 6*x;
P[n_, x_] := P[n, x] = Expand[(3*x - 6*x^2 + x^3)*P[n - 3, x] + (2*x - 3*x^2)*D[P[n - 3, x], x] + (x^2 - x^3)*D[P[n - 3, x], {x, 2}] + (1 + 6*x - 3*x^2)*P[n - 2, x] + 2*x*D[P[n - 2, x], x] + x^2*D[P[n - 2, x], {x, 2}] + 3*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] = 0; v[2] = 2; v[3] = 2 + 6*x; for(n = 3, N, my(i = n + 1); v[i] = (3*x - 6*x^2 + x^3)*v[i - 3] + (2*x - 3*x^2)*deriv(v[i - 3], x) + (x^2 - x^3)*deriv(deriv(v[i - 3], x), x) + (1 + 6*x - 3*x^2)*v[i - 2] + 2*x*deriv(v[i - 2], x) + x^2*deriv(deriv(v[i - 2], x), x) + 3*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)

polytool c48629374597

Properties

Proof chains ? JSON

Same fingerprint ?

References

  1. [ASW52] Michael Aissen, I. J. Schoenberg and A. M. Whitney. On the generating functions of totally positive sequences I. Journal d’Analyse Mathématique, 2(1):93–103, 1952. doi:10.1007/BF02786970
  2. [AW24] Christos A. Athanasiadis and David G. Wagner. Veronese sections and interlacing matrices of polynomials and formal power series. arXiv:2404.12989. arXiv
  3. [Bra06] Petter Brändén. On linear transformations preserving the Pólya frequency property. Transactions of the American Mathematical Society, 358(8):3697–3716, February 2006. doi:10.1090/s0002-9947-06-03856-6
  4. [Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
  5. [Edr53] Albert Edrei. Proof of a Conjecture of Schoenberg on the Generating Function of a Totally Positive Sequence. Canadian Journal of Mathematics, 5:86–94, 1953. doi:10.4153/CJM-1953-010-3
  6. [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
  7. [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
  8. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.