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

only rational roots

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
2-1-2-3
31438
4-1-6-9-4-20
5181816548
6-1-10-30-40-25-6-112
7112458075367256
8-1-14-63-140-175-126-49-8-576
Technical details
Node id
n-568ba9e14bf4b258 · revision 0 · JSON
Definition source
derived:theta_plus_one
Fingerprint
f6-e99c3824c4864868

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: -1,  -2;
   3:  1,   4,    3;
   4: -1,  -6,   -9,   -4;
   5:  1,   8,   18,   16,    5;
   6: -1, -10,  -30,  -40,  -25,   -6;
   7:  1,  12,   45,   80,   75,   36,    7;
   8: -1, -14,  -63, -140, -175, -126,  -49,   -8;
   9:  1,  16,   84,  224,  350,  336,  196,   64,   9;
  10: -1, -18, -108, -336, -630, -756, -588, -288, -81, -10;
%F Formula
The row polynomials satisfy (1+(n-1)*x)*P(n,x) = -(1+(n+1)*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[(-(1 + (n + 1)*x + n*x^2)*P[n - 1, x])/(1 + (n - 1)*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] = (-(1 + (n + 1)*x + n*x^2)*v[i - 1])/(1 + (n - 1)*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.