A038271 → basis A013611 → D

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Submission text ?

Triangle begins:
  0:           0;
  1:          20;
  2:         480,           800;
  3:        8640,         28800,         24000;
  4:      138240,        691200,       1152000,         640000;
  5:     2073600,      13824000,      34560000,       38400000,       16000000;
  6:    29859840,     248832000,     829440000,     1382400000,     1152000000,      384000000;
  7:   418037760,    4180377600,   17418240000,    38707200000,    48384000000,    32256000000,     8960000000;
  8:  5733089280,   66886041600,  334430208000,   928972800000,  1548288000000,  1548288000000,   860160000000,   204800000000;
  9: 77396705280, 1031956070400, 6019743744000, 20065812480000, 41803776000000, 55738368000000, 46448640000000, 22118400000000, 4608000000000;

The row polynomials satisfy (n-1)*P(n,x) = (12*n+20*n*x)*P(n-1,x) for n >= 2, with P(0,x) = 0, P(1,x) = 20.

P[0, x_] := 0;
P[1, x_] := 20;
P[n_, x_] := P[n, x] = Expand[Together[((12*n + 20*n*x)*P[n - 1, x])/(n - 1)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten

P(N) = {my(v = vector(N + 1)); v[1] = 0; v[2] = 20; for(n = 2, N, my(i = n + 1); v[i] = ((12*n + 20*n*x)*v[i - 1])/(n - 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_A013611 of Triangle whose (i,j)-th entry is binomial(i,j)*7^(i-j)*5^j.?
    • Geometric basis map (elementary) polytool ? step ›

      • from Triangle whose (i,j)-th entry is binomial(i,j)*7^(i-j)*5^j.?
        • 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
        • Liu–Wang theorem [LW07, Thm 2.1, Cor 2.4] ? step › direct check
        • 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 ?

• A178822 → basis A013610 → basis A007318
• A013622: Triangle of coefficients in expansion of (3+5x)^n.
• A085880 → basis A013610 → x ↦ x+1
• A178820 → basis A013610 → x ↦ x+1
• A120910 → basis A013609 → x ↦ x/(x+1)
• A038284 → basis A007318 → basis A013609
• A013620 → basis A007318 → D
• A027467 → basis A013611 → basis A013610
• A013622 → basis A013609 → basis A013610
• A038221 → basis A013610 → basis A007318
• A013620 → basis A007318
• A178821 → basis A013610 → x ↦ x+1
• A013622 → D
• A038243 → basis A013611 → x ↦ x/(x+1)
• A038329 → basis A013610
• A156992 → basis A013610 → x ↦ x+1
• A038338 → basis A013610 → x ↦ x+1
• A038329 → basis A013610 → D
• A038231 → D → basis A013610
• A013612 → basis A013609 → D
• A013612 → basis A013609 → reverse
• A038334 → x ↦ x/(x+1)
• A038329 → basis A013610 → reverse
• A013612 → basis A013609
• A038335 → x ↦ x+1 → basis A013609
• A038319 → basis A013611 → basis A013610
• A196347 → basis A013610 → basis A007318
• A038271 → basis A013610 → basis A013610
• A028326 → basis A013610 → x ↦ x+1
• A038255 → basis A013610 → basis A013609
• A038271 → basis A013611

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.