Real-rooted atlas

A028421 → D

nonnegative coefficients

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

Recurrence

\(P_{n}(x) = \left(-8 + 12\,x - 6\,x^{2} + x^{3} + 12\,n - 12\,n x + 3\,n x^{2} - 6\,n^{2} + 3\,n^{2} x + n^{3}\right)\,P_{n-3}(x) + \left(-7 + 9\,x - 3\,x^{2} + 9\,n - 6\,n x - 3\,n^{2}\right)\,P_{n-2}(x) + \left(-3 + 3\,x + 3\,n\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 0\)
\(P_{1}(x) = 2\)
\(P_{2}(x) = 6 + 6\,x\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13Pn(1)
00
122
26612
322361270
410021012020450
554813501020300303248
635289744882035006304226264
7261367879281228392009660117656236248
8219168708744807408448980136080229322016722345400
9205315270362008684160538650018981903969004872032409025507152
102125728076521456100914000683386002706165066264661016400950404950110301835952
11241087680905507856126309691291991460040018605011077743620015688235224017325072601323863119104
122972885760115893573121696817865613144136720618210450018895897023878915045396133650193002988701029615653193434112
133960551808015958030233624376503715219915407512010008356358033219612426756204248812002150161327025701002001049249214196182784313595648
145669312947202352940786944373187112480031944321136001699901002800605191562976150161411400265256362803358104750302472170189189007807801911021012331635229440
Technical details
Node id
n-547ffb202e0ef3e7 · revision 0 · JSON
Definition source
derived:derivative
Fingerprint
f6-86ccdfaf0e2feef5

Observed on the stored rows ?

  • Degrees: -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 (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 = 0, …, ascending powers of x
%e Example
Triangle begins:
  0:       0;
  1:       2;
  2:       6,       6;
  3:      22,      36,      12;
  4:     100,     210,     120,      20;
  5:     548,    1350,    1020,     300,      30;
  6:    3528,    9744,    8820,    3500,     630,     42;
  7:   26136,   78792,   81228,   39200,    9660,   1176,    56;
  8:  219168,  708744,  807408,  448980,  136080,  22932,  2016,   72;
  9: 2053152, 7036200, 8684160, 5386500, 1898190, 396900, 48720, 3240, 90;
%F Formula
The row polynomials satisfy P(n,x) = (n^3-6*n^2+12*n-8+(3*n^2-12*n+12)*x+(3*n-6)*x^2+x^3)*P(n-3,x) - (3*n^2-9*n+7+(6*n-9)*x+3*x^2)*P(n-2,x) + (3*n-3+3*x)*P(n-1,x) for n >= 3, with P(0,x) = 0, P(1,x) = 2, P(2,x) = 6 + 6*x.
%t Mathematica
P[0, x_] := 0;
P[1, x_] := 2;
P[2, x_] := 6 + 6*x;
P[n_, x_] := P[n, x] = Expand[(n^3 - 6*n^2 + 12*n - 8 + (3*n^2 - 12*n + 12)*x + (3*n - 6)*x^2 + x^3)*P[n - 3, x] - (3*n^2 - 9*n + 7 + (6*n - 9)*x + 3*x^2)*P[n - 2, x] + (3*n - 3 + 3*x)*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] = 0; v[2] = 2; v[3] = 6 + 6*x; for(n = 3, N, my(i = n + 1); v[i] = (n^3 - 6*n^2 + 12*n - 8 + (3*n^2 - 12*n + 12)*x + (3*n - 6)*x^2 + x^3)*v[i - 3] - (3*n^2 - 9*n + 7 + (6*n - 9)*x + 3*x^2)*v[i - 2] + (3*n - 3 + 3*x)*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. [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.