Real-rooted atlas

A127648 → Veronese 2 → D

palindromicγ-positivenonnegative coefficientsonly rational roots

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

Recurrence

\(\left(15 - 8\,n + n^{2}\right)\,P_{n}(x) = \left(-3\,x^{2} + 4\,n x^{2} - n^{2} x^{2}\right)\,P_{n-4}(x) + \left(10\,x - 12\,n x + 2\,n^{2} x\right)\,P_{n-2}(x)\)
\(P_{0}(x) = 0\)
\(P_{1}(x) = 0\)
\(P_{2}(x) = 0\)
\(P_{3}(x) = 3\)
\(P_{4}(x) = 0\)
\(P_{5}(x) = 10\,x\)

Rows ?

nx0x1x2x3x4x5Pn(1)
00
10
20
333
40
501010
60
7002121
80
90003636
100
1100005555
120
13000007878
140
Technical details
Node id
n-1b80dfbc39d0c7be · revision 0 · JSON
Definition source
derived:derivative
Fingerprint
f6-1641c37dbfc60bc3

Observed on the stored rows ?

  • Degrees: -1, -1, -1, 0, -1, 1, -1, 2, -1, 3, -1, 4, -1, 5, -1 (half affine: slope 1, 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

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 0, …, ascending powers of x
%e Example
Triangle begins:
  0: 0;
  1: 0;
  2: 0;
  3: 3;
  4: 0;
  5: 0, 10;
  6: 0;
  7: 0,  0, 21;
  8: 0;
  9: 0,  0,  0, 36;
%F Formula
The row polynomials satisfy (n^2-8*n+15)*P(n,x) = -(n^2-4*n+3)*x^2*P(n-4,x) + (2*n^2-12*n+10)*x*P(n-2,x) for n >= 6, with P(0,x) = 0, P(1,x) = 0, P(2,x) = 0, P(3,x) = 3, P(4,x) = 0, P(5,x) = 10*x.
%t Mathematica
P[0, x_] := 0;
P[1, x_] := 0;
P[2, x_] := 0;
P[3, x_] := 3;
P[4, x_] := 0;
P[5, x_] := 10*x;
P[n_, x_] := P[n, x] = Expand[Together[(-(n^2 - 4*n + 3)*x^2*P[n - 4, x] + (2*n^2 - 12*n + 10)*x*P[n - 2, x])/(n^2 - 8*n + 15)]];
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] = 0; v[4] = 3; v[5] = 0; v[6] = 10*x; for(n = 6, N, my(i = n + 1); v[i] = (-(n^2 - 4*n + 3)*x^2*v[i - 4] + (2*n^2 - 12*n + 10)*x*v[i - 2])/(n^2 - 8*n + 15)); 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. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.