Veronese parent of A098172 → D

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Submission text ?

Triangle begins:
   1: 0, 2;
   2: 0, 0, 0, 4, 5;
   3: 0, 0, 0, 0, 0, 6, 14, 8;
   4: 0, 0, 0, 0, 0, 0,  0, 8, 27, 30, 11;
   5: 0, 0, 0, 0, 0, 0,  0, 0,  0, 10, 44, 72, 52,  14;
   6: 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0, 12, 65, 140, 150,  80,  17;
   7: 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  0,  14,  90, 240, 340, 270, 114,  20;
   8: 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  0,   0,   0,  16, 119, 378, 665, 700,  441,  154,   23;
   9: 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  0,   0,   0,   0,   0,  18, 152, 560, 1176, 1540, 1288,  672,  200,   26;
  10: 0, 0, 0, 0, 0, 0,  0, 0,  0,  0,  0,  0,  0,   0,   0,   0,   0,   0,   0,  20,  189,  792, 1932, 3024, 3150, 2184, 972, 252, 29;

The row polynomials satisfy (2*n-2+(3*n-4)*x)*P(n,x) = (2*n*x^2+(5*n-1)*x^3+(3*n-1)*x^4)*P(n-1,x) for n >= 2, with P(1,x) = 2*x.

P[1, x_] := 2*x;
P[n_, x_] := P[n, x] = Expand[Together[((2*n*x^2 + (5*n - 1)*x^3 + (3*n - 1)*x^4)*P[n - 1, x])/(2*n - 2 + (3*n - 4)*x)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten

P(N) = {my(v = vector(N)); v[1] = 2*x; for(n = 2, N, my(i = n); v[i] = ((2*n*x^2 + (5*n - 1)*x^3 + (3*n - 1)*x^4)*v[i - 1])/(2*n - 2 + (3*n - 4)*x)); 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)

Properties

• Real-rooted? Every row P_n, n ≥ 1, is zero or real-rooted with all roots in (−∞, 0]
  by Laguerre’s theorem on differential operators, Laguerre’s theorem on multiplier sequences
• Coefficients of one sign? Every nonzero row, n ≥ 1: the coefficients of P_n have one sign
  derived from Laguerre’s theorem on differential operators, Laguerre’s theorem on multiplier sequences
• Hadamard kernel (Malo)? Rows P_n, n ≥ 1, are Hadamard kernels (preserve real-rootedness)
  derived from Laguerre’s theorem on differential operators, Laguerre’s theorem on multiplier sequences

Proof chains ? JSON

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

  • from veronese parent of Triangle T(n,k) with diagonals T(n,n-k) = binomial(n,3k).?
    • 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
    • Row-hypergeometric rows (multiplier sequences) [SP14; Bra15, Thm 7.1 of arXiv:1410.6601] polytool RealRooted RealRooted.isPFMultiplierSequence_eval_of_roots_nonpos RealRooted RealRooted.isPFMultiplierSequence_inv_ascPochhammer RealRooted RealRooted.IsPFMultiplierSequence.mul ? step › direct check
• Laguerre’s theorem on multiplier sequences [SP14; Bra15, Thm 7.1 of arXiv:1410.6601] polytool ? step ›

  • from veronese parent of Triangle T(n,k) with diagonals T(n,n-k) = binomial(n,3k).?
    • 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
    • Row-hypergeometric rows (multiplier sequences) [SP14; Bra15, Thm 7.1 of arXiv:1410.6601] polytool RealRooted RealRooted.isPFMultiplierSequence_eval_of_roots_nonpos RealRooted RealRooted.isPFMultiplierSequence_inv_ascPochhammer RealRooted RealRooted.IsPFMultiplierSequence.mul ? step › direct check

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.