basis-map coefficients of A021012 → θ+1 → D+1

only rational roots

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
2-2-2-4
3012618
400-72-24-96
5000480120600
60000-3600-720-4320
70000030240504035280
8000000-282240-40320-322560
Technical details
Node id
n-c5b5d802fc81fcee · revision 0 · JSON
Definition source
derived:one_plus_derivative
Fingerprint
f6-2327141074f67bdf

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 -1)
  • Palindromic rows: no
  • γ-positive (gamma_positive): no
  • Nonnegative coefficients (nonn): no
  • 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 = 1, …, ascending powers of x
%e Example
Triangle begins:
   1:  1;
   2: -2, -2;
   3:  0, 12,   6;
   4:  0,  0, -72, -24;
   5:  0,  0,   0, 480,   120;
   6:  0,  0,   0,   0, -3600,  -720;
   7:  0,  0,   0,   0,     0, 30240,    5040;
   8:  0,  0,   0,   0,     0,     0, -282240,  -40320;
   9:  0,  0,   0,   0,     0,     0,       0, 2903040,    362880;
  10:  0,  0,   0,   0,     0,     0,       0,       0, -32659200, -3628800;
%F Formula
The row polynomials satisfy (n-2+x)*P(n,x) = -((n^2-n)*x+n*x^2)*P(n-1,x) for n >= 2, with P(1,x) = 1.
%t Mathematica
P[1, x_] := 1;
P[n_, x_] := P[n, x] = Expand[Together[(-((n^2 - n)*x + n*x^2)*P[n - 1, x])/(n - 2 + x)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N)); v[1] = 1; for(n = 2, N, my(i = n); v[i] = (-((n^2 - n)*x + n*x^2)*v[i - 1])/(n - 2 + x)); v};
row(n, p) = {my(c = Vecrev(p)); c};
T(N) = {my(v = P(N)); concat(vector(#v, i, row(i, v[i])))};
T(10)

polytool c48629374597

Properties

Proof chains ? JSON

Same fingerprint ?

References

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