Veronese parent of A098172 → x ↦ x/(x+1)

nonnegative coefficientsonly rational roots

Proved for all n all roots real, in [−1, 0]coefficients of one signHadamard kernel

Recurrence

\(\left(1 + 3\,x + 3\,x^{2} + x^{3}\right)\,P_{n}(x) = \left(x^{2} + 5\,x^{3} + 9\,x^{4} + 7\,x^{5} + 2\,x^{6}\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 1\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16x17x18x19x20x21Pn(1)
111
200123
300001449
40000001612827
5000000001824321681
6000000000011040808032243
70000000000001126016024019264729
800000000000000114842805606724481282187
Technical details
Node id
n-a116f96e8f97e756 · revision 0 · JSON
Definition source
derived:mobius_x_over_x_plus_one
Fingerprint
f6-11aec07ce60b6d61

Observed on the stored rows ?

  • Degrees: 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42 (affine: slope 3, intercept -3)
  • Palindromic rows: no
  • γ-positive (gamma_positive): no
  • 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, 0, 1, 2;
   3: 0, 0, 0, 0, 1, 4, 4;
   4: 0, 0, 0, 0, 0, 0, 1, 6, 12, 8;
   5: 0, 0, 0, 0, 0, 0, 0, 0,  1, 8, 24, 32, 16;
   6: 0, 0, 0, 0, 0, 0, 0, 0,  0, 0,  1, 10, 40, 80, 80,  32;
   7: 0, 0, 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  1, 12, 60, 160, 240, 192,  64;
   8: 0, 0, 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  1,  14,  84, 280, 560, 672,  448,  128;
   9: 0, 0, 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  0,   0,   1,  16, 112, 448, 1120, 1792, 1792, 1024,  256;
  10: 0, 0, 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  0,   0,   0,   0,   1,  18,  144,  672, 2016, 4032, 5376, 4608, 2304, 512;
%F Formula
The row polynomials satisfy (1+3*x+3*x^2+x^3)*P(n,x) = (x^2+5*x^3+9*x^4+7*x^5+2*x^6)*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[((x^2 + 5*x^3 + 9*x^4 + 7*x^5 + 2*x^6)*P[n - 1, x])/(1 + 3*x + 3*x^2 + x^3)]];
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] = ((x^2 + 5*x^3 + 9*x^4 + 7*x^5 + 2*x^6)*v[i - 1])/(1 + 3*x + 3*x^2 + x^3)); 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.