Real-rooted atlas

A088996 → θ+1

nonnegative coefficients

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
011
1022
20268
304212449
401287184120403
5048438131616307204152
602402622100841802015336504051342
701440182528497619635524338415548440320740211

All 15 rows

Technical details
Node id
n-92d6e06b89093e78 · revision 0 · JSON
Definition source
derived:theta_plus_one
Fingerprint
f6-6ea9ebd1c906150f

Observed on the stored rows ?

  • Degrees: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 (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: 0,     2;
  2: 0,     2,       6;
  3: 0,     4,      21,      24;
  4: 0,    12,      87,     184,      120;
  5: 0,    48,     438,    1316,     1630,      720;
  6: 0,   240,    2622,   10084,    18020,    15336,     5040;
  7: 0,  1440,   18252,   84976,   196355,   243384,   155484,    40320;
  8: 0, 10080,  145044,  789520,  2224245,  3588696,  3359972,  1703808,   362880;
  9: 0, 80640, 1296432, 8056688, 26676060, 52731414, 64561084, 48190176, 20154096, 3628800;
%F Formula
The row polynomials satisfy (n-1)*P(n,x) = -(n^3-4*n^2+4*n+(2*n^3-6*n^2+4*n)*x+(n^3-2*n^2+n)*x^2)*P(n-2,x) + (2*n^2-4*n+1+(2*n^2-2*n)*x)*P(n-1,x) for n >= 2, with P(0,x) = 1, P(1,x) = 2*x.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 2*x;
P[n_, x_] := P[n, x] = Expand[Together[(-(n^3 - 4*n^2 + 4*n + (2*n^3 - 6*n^2 + 4*n)*x + (n^3 - 2*n^2 + n)*x^2)*P[n - 2, x] + (2*n^2 - 4*n + 1 + (2*n^2 - 2*n)*x)*P[n - 1, x])/(n - 1)]];
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*x; for(n = 2, N, my(i = n + 1); v[i] = (-(n^3 - 4*n^2 + 4*n + (2*n^3 - 6*n^2 + 4*n)*x + (n^3 - 2*n^2 + n)*x^2)*v[i - 2] + (2*n^2 - 4*n + 1 + (2*n^2 - 2*n)*x)*v[i - 1])/(n - 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

References

  1. [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
  2. [Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
  3. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.