Real-rooted atlas

A106246 → θ+1 → reverse

nonnegative coefficients

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

Recurrence

\(P_{n}(x) = \left(-1\right)\,P_{n-4}(x) + \left(4\right)\,P_{n-3}(x) + \left(-6\right)\,P_{n-2}(x) + \left(4\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 1\)
\(P_{1}(x) = 2 + 2\,x\)
\(P_{2}(x) = 3 + 8\,x + x^{2}\)
\(P_{3}(x) = 4 + 18\,x + 6\,x^{2}\)

Rows ?

nx0x1x2Pn(1)
011
1224
238112
3418628
45321855
56504096
677275154
7898126232

All 15 rows

Technical details
Node id
n-e12320823259851e · revision 0 · JSON
Definition source
derived:reversal
Fingerprint
f6-d6816b839be5a6fb

Observed on the stored rows ?

  • Degrees: 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 (irregular)
  • 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:  2,   2;
  2:  3,   8,   1;
  3:  4,  18,   6;
  4:  5,  32,  18;
  5:  6,  50,  40;
  6:  7,  72,  75;
  7:  8,  98, 126;
  8:  9, 128, 196;
  9: 10, 162, 288;
%F Formula
The row polynomials satisfy P(n,x) = -P(n-4,x) + 4*P(n-3,x) - 6*P(n-2,x) + 4*P(n-1,x) for n >= 4, with P(0,x) = 1, P(1,x) = 2 + 2*x, P(2,x) = 3 + 8*x + x^2, P(3,x) = 4 + 18*x + 6*x^2.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 2 + 2*x;
P[2, x_] := 3 + 8*x + x^2;
P[3, x_] := 4 + 18*x + 6*x^2;
P[n_, x_] := P[n, x] = Expand[-P[n - 4, x] + 4*P[n - 3, x] - 6*P[n - 2, x] + 4*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] = 1; v[2] = 2 + 2*x; v[3] = 3 + 8*x + x^2; v[4] = 4 + 18*x + 6*x^2; for(n = 4, N, my(i = n + 1); v[i] = -v[i - 4] + 4*v[i - 3] - 6*v[i - 2] + 4*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. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.