basis-map coefficients of A026729, shifted → (θ+1)² → basis A013609

only rational roots

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
2-4-8-12
39363681
4-16-96-192-128-432
5252006008004002025
6-36-360-1440-2880-2880-1152-8748
74958829407840117609408313635721
8-64-896-5376-17920-35840-43008-28672-8192-139968
Technical details
Node id
n-252c73401458f7fc · revision 0 · JSON
Definition source
derived:basis_map_A013609
Fingerprint
f6-11aec07ce60b6d61

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:   -4,    -8;
   3:    9,    36,     36;
   4:  -16,   -96,   -192,   -128;
   5:   25,   200,    600,    800,     400;
   6:  -36,  -360,  -1440,  -2880,   -2880,   -1152;
   7:   49,   588,   2940,   7840,   11760,    9408,    3136;
   8:  -64,  -896,  -5376, -17920,  -35840,  -43008,  -28672,   -8192;
   9:   81,  1296,   9072,  36288,   90720,  145152,  145152,   82944,   20736;
  10: -100, -1800, -14400, -67200, -201600, -403200, -537600, -460800, -230400, -51200;
%F Formula
The row polynomials satisfy (n^2-2*n+1)*P(n,x) = -(n^2+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 + 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 + 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.