A143491 → basis A013610 → D+1

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Submission text ?

Triangle begins:
  0:          33,          39,            9;
  1:         201,         357,          189,           27;
  2:        1386,        3168,         2529,          810,           81;
  3:       10782,       29412,        30420,        14715,         3240,         243;
  4:       93816,      292428,       363321,       228825,        76140,       12393,         729;
  5:      904824,     3134268,      4475331,      3403323,      1479870,      364014,       45927,       2187;
  6:     9592560,    36227304,     57772440,     50729112,     26743689,     8620668,     1643166,     166212,       6561;
  7:   110961360,   450612504,    786852468,    774885420,    473527782,   185672655,    46478124,    7099002,     590490,     19683;
  8:  1391411520,  6013243008,  11333481444,  12266230140,   8436391785,  3846891447,  1174552407,  235999170,   29622915,   2066715,   59049;
  9: 18806852160, 85802125824, 172666986228, 202364251452, 153445752405, 78985805481, 28122127803, 6907558581, 1142106075, 120164715, 7144929, 177147;

The row polynomials satisfy P(n,x) = -(n^2+6*n+9+(6*n+18)*x+9*x^2)*P(n-2,x) + (2*n+7+6*x)*P(n-1,x) for n >= 2, with P(0,x) = 33 + 39*x + 9*x^2, P(1,x) = 201 + 357*x + 189*x^2 + 27*x^3.

P[0, x_] := 33 + 39*x + 9*x^2;
P[1, x_] := 201 + 357*x + 189*x^2 + 27*x^3;
P[n_, x_] := P[n, x] = Expand[-(n^2 + 6*n + 9 + (6*n + 18)*x + 9*x^2)*P[n - 2, x] + (2*n + 7 + 6*x)*P[n - 1, x]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten

P(N) = {my(v = vector(N + 1)); v[1] = 33 + 39*x + 9*x^2; v[2] = 201 + 357*x + 189*x^2 + 27*x^3; for(n = 2, N, my(i = n + 1); v[i] = -(n^2 + 6*n + 9 + (6*n + 18)*x + 9*x^2)*v[i - 2] + (2*n + 7 + 6*x)*v[i - 1]); 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 Laguerre’s theorem on differential operators
• Coefficients of one sign? Every nonzero row, n ≥ 0: the coefficients of P_n have one sign
  derived from Laguerre’s theorem on differential operators
• Hadamard kernel (Malo)? Rows P_n, n ≥ 0, are Hadamard kernels (preserve real-rootedness)
  derived from Laguerre’s theorem on differential operators
• Interlacing of consecutive rows? Rows P_(m-1), P_m interlace (weak, unordered) for every m ≥ 1
  by Laguerre’s theorem on differential operators

Proof chains ? JSON

• Laguerre’s theorem on differential operators [SP14] polytool ? step ›

  • from basis_map_A013610 of Unsigned 2-Stirling numbers of the first kind.?
    • Geometric basis map (elementary) polytool ? 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
    • Geometric basis map (elementary) polytool ? 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 ?

• A136124 → basis A013610 → D+1

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. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.