basis-map coefficients of A026729, shifted → (θ+1)² → basis A007318

palindromiconly rational roots

Proved for all n all roots real, in (−∞, −1]coefficients of one signHadamard kernelinterlacing (weak)

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
2-4-4-8
3918936
4-16-48-48-16-128
52510015010025400
6-36-180-360-360-180-36-1152
749294735980735294493136
8-64-448-1344-2240-2240-1344-448-64-8192
Technical details
Node id
n-c14417d0739d6759 · revision 0 · JSON
Definition source
derived:shift_x_plus_one
Fingerprint
f6-77a7ed3b1d5f257e

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: yes
  • 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:   -4,   -4;
   3:    9,   18,     9;
   4:  -16,  -48,   -48,   -16;
   5:   25,  100,   150,   100,     25;
   6:  -36, -180,  -360,  -360,   -180,    -36;
   7:   49,  294,   735,   980,    735,    294,    49;
   8:  -64, -448, -1344, -2240,  -2240,  -1344,  -448,   -64;
   9:   81,  648,  2268,  4536,   5670,   4536,  2268,   648,   81;
  10: -100, -900, -3600, -8400, -12600, -12600, -8400, -3600, -900, -100;
%F Formula
The row polynomials satisfy (n^2-2*n+1)*P(n,x) = -(n^2+n^2*x)*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^2*x)*P[n - 1, x])/(n^2 - 2*n + 1)]];
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^2*x)*v[i - 1])/(n^2 - 2*n + 1)); 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.