Real-rooted atlas

A039755 → reverse → θ+1

nonnegative coefficients

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

Recurrence

\(\left(-3 + 2\,n\right)\,P_{n}(x) = \left(1 - 10\,x + 15\,x^{2} - 2\,n + 24\,n x - 46\,n x^{2} - 8\,n^{2} x + 36\,n^{2} x^{2} - 8\,n^{3} x^{2}\right)\,P_{n-2}(x) + \left(-2\,x^{2} + 6\,x^{3} + 4\,n x^{2} - 16\,n x^{3} + 8\,n^{2} x^{3}\right)\,P_{n-2}'(x) + \left(-4 + 18\,x + 4\,n - 24\,n x + 8\,n^{2} x\right)\,P_{n-1}(x) + \left(6\,x^{2} - 4\,n x^{2}\right)\,P_{n-1}'(x)\)
\(P_{1}(x) = 1\)
\(P_{2}(x) = 1 + 2\,x\)

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
2123
318312
411839462
51321741605372
6150510132060562492
71721185608088552184718384
8198237320300620555531476518147800

All 15 rows

Technical details
Node id
n-da1d7369c76900d7 · revision 0 · JSON
Definition source
derived:theta_plus_one
Fingerprint
f6-1ea903b913797f87

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): 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 = 1, …, ascending powers of x
%e Example
Triangle begins:
   1: 1;
   2: 1,   2;
   3: 1,   8,    3;
   4: 1,  18,   39,      4;
   5: 1,  32,  174,    160,       5;
   6: 1,  50,  510,   1320,     605,       6;
   7: 1,  72, 1185,   6080,    8855,    2184,       7;
   8: 1,  98, 2373,  20300,   62055,   55314,    7651,       8;
   9: 1, 128, 4284,  55104,  290430,  576576,  330316,   26240,     9;
  10: 1, 162, 7164, 129360, 1048110, 3713220, 5039020, 1913760, 88569, 10;
%F Formula
The row polynomials satisfy (2*n-3)*P(n,x) = -(2*n-1+(8*n^2-24*n+10)*x+(8*n^3-36*n^2+46*n-15)*x^2)*P(n-2,x) + ((4*n-2)*x^2+(8*n^2-16*n+6)*x^3)*d/dx P(n-2,x) + (4*n-4+(8*n^2-24*n+18)*x)*P(n-1,x) - (4*n-6)*x^2*d/dx P(n-1,x) for n >= 3, with P(1,x) = 1, P(2,x) = 1 + 2*x.
%t Mathematica
P[1, x_] := 1;
P[2, x_] := 1 + 2*x;
P[n_, x_] := P[n, x] = Expand[Together[(-(2*n - 1 + (8*n^2 - 24*n + 10)*x + (8*n^3 - 36*n^2 + 46*n - 15)*x^2)*P[n - 2, x] + ((4*n - 2)*x^2 + (8*n^2 - 16*n + 6)*x^3)*D[P[n - 2, x], x] + (4*n - 4 + (8*n^2 - 24*n + 18)*x)*P[n - 1, x] - (4*n - 6)*x^2*D[P[n - 1, x], x])/(2*n - 3)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N)); v[1] = 1; v[2] = 1 + 2*x; for(n = 3, N, my(i = n); v[i] = (-(2*n - 1 + (8*n^2 - 24*n + 10)*x + (8*n^3 - 36*n^2 + 46*n - 15)*x^2)*v[i - 2] + ((4*n - 2)*x^2 + (8*n^2 - 16*n + 6)*x^3)*deriv(v[i - 2], x) + (4*n - 4 + (8*n^2 - 24*n + 18)*x)*v[i - 1] - (4*n - 6)*x^2*deriv(v[i - 1], x))/(2*n - 3)); 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. [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. [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
  4. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.