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

palindromicγ-positivenonnegative coefficientsonly rational roots

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

Recurrence

\(\left(1 - 4\,n + 6\,n^{2} - 4\,n^{3} + n^{4}\right)\,P_{n}(x) = \left(n^{4} x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 1\)

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
201616
3008181
4000256256
50000625625
60000012961296
700000024012401
8000000040964096
Technical details
Node id
n-969fb1fba8487e2b · revision 0 · JSON
Definition source
derived:theta_plus_one_squared
Fingerprint
f6-edf6954a4cd8adfc

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): 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, 16;
   3: 0,  0, 81;
   4: 0,  0,  0, 256;
   5: 0,  0,  0,   0, 625;
   6: 0,  0,  0,   0,   0, 1296;
   7: 0,  0,  0,   0,   0,    0, 2401;
   8: 0,  0,  0,   0,   0,    0,    0, 4096;
   9: 0,  0,  0,   0,   0,    0,    0,    0, 6561;
  10: 0,  0,  0,   0,   0,    0,    0,    0,    0, 10000;
%F Formula
The row polynomials satisfy (n^4-4*n^3+6*n^2-4*n+1)*P(n,x) = n^4*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^4*x*P[n - 1, x])/(n^4 - 4*n^3 + 6*n^2 - 4*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^4*x*v[i - 1])/(n^4 - 4*n^3 + 6*n^2 - 4*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. [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. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.