A086645 → γ → D

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Triangle begins:
   1:   0;
   2:   0;
   3:   4;
   4:  12;
   5:  24,   32;
   6:  40,  160;
   7:  60,  480,   192;
   8:  84, 1120,  1344;
   9: 112, 2240,  5376, 1024;
  10: 144, 4032, 16128, 9216;

The row polynomials satisfy (n^2-5*n+6)*P(n,x) = (n^2-3*n+2+(4*n^2-20*n+16)*x)*P(n-1,x) + ((2*n-2)*x-(8*n-8)*x^2)*d/dx P(n-1,x) for n >= 4, with P(1,x) = 0, P(2,x) = 0, P(3,x) = 4.

P[1, x_] := 0;
P[2, x_] := 0;
P[3, x_] := 4;
P[n_, x_] := P[n, x] = Expand[Together[((n^2 - 3*n + 2 + (4*n^2 - 20*n + 16)*x)*P[n - 1, x] + ((2*n - 2)*x - (8*n - 8)*x^2)*D[P[n - 1, x], x])/(n^2 - 5*n + 6)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten

P(N) = {my(v = vector(N)); v[1] = 0; v[2] = 0; v[3] = 4; for(n = 4, N, my(i = n); v[i] = ((n^2 - 3*n + 2 + (4*n^2 - 20*n + 16)*x)*v[i - 1] + ((2*n - 2)*x - (8*n - 8)*x^2)*deriv(v[i - 1], x))/(n^2 - 5*n + 6)); 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
• 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
• Hadamard kernel (Malo)? Rows P_n, n ≥ 1, are Hadamard kernels (preserve real-rootedness)
  derived from Laguerre’s theorem on differential operators

Proof chains ? JSON

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

  • from gamma_polynomial of Triangle read by rows: T(n, k) = binomial(2n, 2k).?
    • Gamma criterion RealRooted IsGammaExpansion.isRealRooted_and_hasRootsNonpos_iff ? step ›

      • from Triangle read by rows: T(n, k) = binomial(2n, 2k).?
        • Three-term recurrence criterion [Sze39, §3.3; Fav35] polytool ? step › direct check
        • Liu–Wang theorem for three-term recurrences [LW07, Thm 2.1, Thm 2.3, Cor 2.4, Prop 3.3] polytool ? step › direct check
        • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

          • from Triangle read by rows: T(n, k) = binomial(2n, 2k).?
            • ↑ Three-term recurrence criterion (above)
            • ↑ Liu–Wang theorem for three-term recurrences (above)
            • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

              • from Triangle read by rows: T(n, k) = binomial(2n, 2k).?
                • ↑ Three-term recurrence criterion (above)
                • ↑ Liu–Wang theorem for three-term recurrences (above)
        • ↑ Affine, reversal and Möbius substitutions (elementary) (above)

Related ?

Same fingerprint ?

• A013609 → Veronese 2 → D
• A120909 → Veronese 2 (j=1)
• A229032: Triangle T(n,k), 0 <= k <= n, read by rows, defined by T(n,k) = 4^k * C(n+1,2*k+1).
• A013609 → Veronese 2 (j=1)

References

1. [Fav35] Jean Favard. Sur les polynômes de tchebicheff. C. R. Acad. Sci. Paris, 200:2052–2053, 1935.
2. [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
3. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.
4. [Sze39] G. Szegő. Orthogonal Polynomials. Colloquium publications, American Mathematical Society, 1939. doi:10.1090/coll/023