Real-rooted atlas

A119462 → (θ+1)²

nonnegative coefficients

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

Recurrence

\(\left(-36 - 12\,x + 36\,n + 10\,n x + 24\,n^{2} x - n^{2} x^{2} - 22\,n^{3} x - n^{3} x^{2} + n^{4} x^{2} + n^{5} x^{2}\right)\,P_{n}(x) = \left(-36 - 156\,x + 4\,x^{2} - 4\,x^{3} + 36\,n + 154\,n x + 62\,n x^{2} - 8\,n x^{3} + 24\,n^{2} x - 29\,n^{2} x^{2} - n^{2} x^{3} - 22\,n^{3} x - 39\,n^{3} x^{2} + 7\,n^{3} x^{3} + n^{4} x^{2} + 5\,n^{4} x^{3} + n^{5} x^{2} + n^{5} x^{3}\right)\,P_{n-1}(x) + \left(72\,x - 88\,x^{2} + 24\,x^{3} - 8\,x^{4} - 84\,n x^{2} + 108\,n x^{3} - 24\,n x^{4} - 44\,n^{2} x^{2} + 70\,n^{2} x^{3} - 26\,n^{2} x^{4} + 12\,n^{3} x^{3} - 12\,n^{3} x^{4} + 2\,n^{4} x^{3} - 2\,n^{4} x^{4}\right)\,P_{n-1}'(x)\)
\(P_{0}(x) = 1\)
\(P_{1}(x) = 2\)

Rows ?

nx0x1x2x3Pn(1)
011
122
22810
322426
42481868
528090172
6212027032424
721686302241024

All 15 rows

Technical details
Node id
n-202941dcb2123fea · revision 0 · JSON
Definition source
derived:theta_plus_one_squared
Fingerprint
f6-1f0181c04d99414a

Observed on the stored rows ?

  • Degrees: 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7 (half 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: 2;
  2: 2,   8;
  3: 2,  24;
  4: 2,  48,   18;
  5: 2,  80,   90;
  6: 2, 120,  270,   32;
  7: 2, 168,  630,  224;
  8: 2, 224, 1260,  896,  50;
  9: 2, 288, 2268, 2688, 450;
%F Formula
The row polynomials satisfy (36*n-36-(22*n^3-24*n^2-10*n+12)*x+(n^5+n^4-n^3-n^2)*x^2)*P(n,x) = (36*n-36-(22*n^3-24*n^2-154*n+156)*x+(n^5+n^4-39*n^3-29*n^2+62*n+4)*x^2+(n^5+5*n^4+7*n^3-n^2-8*n-4)*x^3)*P(n-1,x) + (72*x-(44*n^2+84*n+88)*x^2+(2*n^4+12*n^3+70*n^2+108*n+24)*x^3-(2*n^4+12*n^3+26*n^2+24*n+8)*x^4)*d/dx P(n-1,x) for n >= 2, with P(0,x) = 1, P(1,x) = 2.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 2;
P[n_, x_] := P[n, x] = Expand[Together[((36*n - 36 - (22*n^3 - 24*n^2 - 154*n + 156)*x + (n^5 + n^4 - 39*n^3 - 29*n^2 + 62*n + 4)*x^2 + (n^5 + 5*n^4 + 7*n^3 - n^2 - 8*n - 4)*x^3)*P[n - 1, x] + (72*x - (44*n^2 + 84*n + 88)*x^2 + (2*n^4 + 12*n^3 + 70*n^2 + 108*n + 24)*x^3 - (2*n^4 + 12*n^3 + 26*n^2 + 24*n + 8)*x^4)*D[P[n - 1, x], x])/(36*n - 36 - (22*n^3 - 24*n^2 - 10*n + 12)*x + (n^5 + n^4 - n^3 - n^2)*x^2)]];
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; for(n = 2, N, my(i = n + 1); v[i] = ((36*n - 36 - (22*n^3 - 24*n^2 - 154*n + 156)*x + (n^5 + n^4 - 39*n^3 - 29*n^2 + 62*n + 4)*x^2 + (n^5 + 5*n^4 + 7*n^3 - n^2 - 8*n - 4)*x^3)*v[i - 1] + (72*x - (44*n^2 + 84*n + 88)*x^2 + (2*n^4 + 12*n^3 + 70*n^2 + 108*n + 24)*x^3 - (2*n^4 + 12*n^3 + 26*n^2 + 24*n + 8)*x^4)*deriv(v[i - 1], x))/(36*n - 36 - (22*n^3 - 24*n^2 - 10*n + 12)*x + (n^5 + n^4 - n^3 - n^2)*x^2)); 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. [Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
  2. [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
  3. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.