A143491 → basis A008277 → reverse

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Submission text ?

Triangle begins:
  0: 1,   8,   12;
  1: 1,  15,   60,     60;
  2: 1,  24,  180,    480,     360;
  3: 1,  35,  420,   2100,    4200,     2520;
  4: 1,  48,  840,   6720,   25200,    40320,     20160;
  5: 1,  63, 1512,  17640,  105840,   317520,    423360,     181440;
  6: 1,  80, 2520,  40320,  352800,  1693440,   4233600,    4838400,    1814400;
  7: 1,  99, 3960,  83160,  997920,  6985440,  27941760,   59875200,   59875200,    19958400;
  8: 1, 120, 5940, 158400, 2494800, 23950080, 139708800,  479001600,  898128000,   798336000,   239500800;
  9: 1, 143, 8580, 283140, 5662800, 71351280, 570810240, 2854051200, 8562153600, 14270256000, 11416204800, 3113510400;

The row polynomials satisfy P(n,x) = (1+(2*n+5)*x)*P(n-1,x) - x^2*d/dx P(n-1,x) for n >= 1, with P(0,x) = 1 + 8*x + 12*x^2.

P[0, x_] := 1 + 8*x + 12*x^2;
P[n_, x_] := P[n, x] = Expand[(1 + (2*n + 5)*x)*P[n - 1, x] - x^2*D[P[n - 1, x], x]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten

P(N) = {my(v = vector(N + 1)); v[1] = 1 + 8*x + 12*x^2; for(n = 1, N, my(i = n + 1); v[i] = (1 + (2*n + 5)*x)*v[i - 1] - x^2*deriv(v[i - 1], x)); v};
row(n, p) = {my(c = Vecrev(p)); c};
T(N) = {my(v = P(N)); concat(vector(#v, i, row(i - 1, v[i])))};
T(9)

Properties

• Real-rooted? Every row P_n, n ≥ 0, is zero or real-rooted with all roots in (−∞, 0]
  by Affine, reversal and Möbius substitutions (elementary)
• Coefficients of one sign? Every nonzero row, n ≥ 0: the coefficients of P_n have one sign
  derived from Affine, reversal and Möbius substitutions (elementary)
• Hadamard kernel (Malo)? Rows P_n, n ≥ 0, are Hadamard kernels (preserve real-rootedness)
  derived from Affine, reversal and Möbius substitutions (elementary)

Proof chains ? JSON

• Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

  • from basis_map_A008277 of Unsigned 2-Stirling numbers of the first kind.?
    • Ray basis map theorem [MW08, Thm 2] polytool RealRooted rayBasisMap_maps_realRootedIn_iff ? step ›

      • from Unsigned 2-Stirling numbers of the first kind.?
        • Liu–Wang theorem [LW07, Thm 2.1, Cor 2.4] ? step › direct check
        • Parent-row provers of polytool polytool ? step › direct check
        • Iterated real-rootedness preservers [SP14; Bra15, Thm 7.1 of arXiv:1410.6601; Bra06, Cor 3.5] polytool ? step › direct check
    • Ray basis map theorem [MW08, Thm 2] polytool RealRooted rayBasisMap_maps_realRootedIn_iff ? step ›

      • from Unsigned 2-Stirling numbers of the first kind.?
        • ↑ Liu–Wang theorem (above)
        • ↑ Parent-row provers of polytool (above)
        • ↑ Iterated real-rootedness preservers (above)

Related ?

Same fingerprint ?

• A143491 → basis A008277
• A105278 → D+1
• A136124 → basis A008277 → reverse
• A105278 → D
• A136124 → basis A008277
• A130534 → basis A008277 → D

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. [LW07] Lily L. Liu and Yi Wang. A unified approach to polynomial sequences with only real zeros. Advances in Applied Mathematics, 38(4):542–560, May 2007. doi:10.1016/j.aam.2006.02.003
4. [MW08] Shi-Mei Ma and Yi Wang. q-Eulerian polynomials and polynomials with only real zeros. The Electronic Journal of Combinatorics, 15(1):Research Paper 17, January 2008. doi:10.37236/741
5. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.