A103633 → basis A013609 → reverse

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Submission text ?

Triangle begins:
  0:   1;
  1:   2,    1;
  2:   4,    6,    2;
  3:   8,   16,   10,     2;
  4:  16,   48,   52,    24,     4;
  5:  32,  112,  152,   100,    32,     4;
  6:  64,  288,  528,   504,   264,    72,    8;
  7: 128,  640, 1344,  1536,  1032,   408,   88,    8;
  8: 256, 1536, 3968,  5760,  5136,  2880,  992,  192,  16;
  9: 512, 3328, 9472, 15488, 16032, 10896, 4864, 1376, 224, 16;

The row polynomials satisfy P(n,x) = (2+(3*n-2)*x+(2*n-2)*x^2)*P(n-1,x) - (4*x+6*x^2+2*x^3)*d/dx P(n-1,x) for n >= 1, with P(0,x) = 1.

P[0, x_] := 1;
P[n_, x_] := P[n, x] = Expand[(2 + (3*n - 2)*x + (2*n - 2)*x^2)*P[n - 1, x] - (4*x + 6*x^2 + 2*x^3)*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; for(n = 1, N, my(i = n + 1); v[i] = (2 + (3*n - 2)*x + (2*n - 2)*x^2)*v[i - 1] - (4*x + 6*x^2 + 2*x^3)*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_A013609 of Triangle read by rows: triangle of repeated stepped binomial coefficients.?
    • Geometric basis map (elementary) polytool ? step ›

      • from Triangle read by rows: triangle of repeated stepped binomial coefficients.?
        • Iterated real-rootedness preservers [SP14; Bra15, Thm 7.1 of arXiv:1410.6601; Bra06, Cor 3.5] polytool ? step › direct check
        • Parent-row provers of polytool polytool ? step › direct check

Related ?

Same fingerprint ?

• A064861 → reverse
• A103633 → basis A013609
• Triangle of Sulanke numbers: T(n,k) = T(n,k-1) + a(n-1,k) for n+k even and a(n,k) = a(n,k-1) + 2*a(n-1,k) for n+k odd.

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.