basis-map coefficients of A021012 → Veronese 2 → x ↦ x+1

palindromicγ-positivenonnegative coefficientsonly rational roots

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

Recurrence

\(P_{n}(x) = \left(2 + 2\,x - 3\,n - 3\,n x + n^{2} + n^{2} x\right)\,P_{n-2}(x)\)
\(P_{1}(x) = 1\)
\(P_{2}(x) = 0\)

Rows ?

nx0x1x2x3Pn(1)
111
20
3224
40
524482496
60
7720216021607205760
80
Technical details
Node id
n-d42ecec45f49e6cd · revision 0 · JSON
Definition source
derived:shift_x_plus_one
Fingerprint
f6-d7f29bf7c3df048c

Observed on the stored rows ?

  • Degrees: 0, -1, 1, -1, 2, -1, 3, -1, 4, -1, 5, -1, 6, -1, 7 (half affine: slope 1, intercept -1)
  • Palindromic rows: yes
  • γ-positive (gamma_positive): yes
  • Nonnegative coefficients (nonn): yes
  • 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:     0;
   3:     2,      2;
   4:     0;
   5:    24,     48,     24;
   6:     0;
   7:   720,   2160,   2160,    720;
   8:     0;
   9: 40320, 161280, 241920, 161280, 40320;
  10:     0;
%F Formula
The row polynomials satisfy P(n,x) = (n^2-3*n+2+(n^2-3*n+2)*x)*P(n-2,x) for n >= 3, with P(1,x) = 1, P(2,x) = 0.
%t Mathematica
P[1, x_] := 1;
P[2, x_] := 0;
P[n_, x_] := P[n, x] = Expand[(n^2 - 3*n + 2 + (n^2 - 3*n + 2)*x)*P[n - 2, x]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N)); v[1] = 1; v[2] = 0; for(n = 3, N, my(i = n); v[i] = (n^2 - 3*n + 2 + (n^2 - 3*n + 2)*x)*v[i - 2]); 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. [ASW52] Michael Aissen, I. J. Schoenberg and A. M. Whitney. On the generating functions of totally positive sequences I. Journal d’Analyse Mathématique, 2(1):93–103, 1952. doi:10.1007/BF02786970
  2. [AW24] Christos A. Athanasiadis and David G. Wagner. Veronese sections and interlacing matrices of polynomials and formal power series. arXiv:2404.12989. arXiv
  3. [Edr53] Albert Edrei. Proof of a Conjecture of Schoenberg on the Generating Function of a Totally Positive Sequence. Canadian Journal of Mathematics, 5:86–94, 1953. doi:10.4153/CJM-1953-010-3