A120910 → Veronese 2 (j=1) → (θ+1)²

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Submission text ?

Triangle begins:
  0:    0;
  1:    3;
  2:   12;
  3:   36,    12;
  4:   96,    96;
  5:  240,   480,    27;
  6:  576,  1920,   324;
  7: 1344,  6720,  2268,   48;
  8: 3072, 21504, 12096,  768;
  9: 6912, 64512, 54432, 6912, 75;

The row polynomials satisfy (128*n-128-(80*n^3-224*n^2+176*n-32)*x+(2*n^5-6*n^4+6*n^3-2*n^2)*x^2)*P(n,x) = (256*n-(160*n^3-288*n^2-192*n+512)*x+(4*n^5-8*n^4-68*n^3+136*n^2+48*n-64)*x^2+(n^5-3*n^3-2*n^2)*x^3)*P(n-1,x) + (512*x-(320*n^2+64*n)*x^2+(8*n^4+16*n^3+88*n^2+16*n-32)*x^3-(2*n^4+4*n^3+2*n^2)*x^4)*d/dx P(n-1,x) for n >= 2, with P(0,x) = 0, P(1,x) = 3.

P[0, x_] := 0;
P[1, x_] := 3;
P[n_, x_] := P[n, x] = Expand[Together[((256*n - (160*n^3 - 288*n^2 - 192*n + 512)*x + (4*n^5 - 8*n^4 - 68*n^3 + 136*n^2 + 48*n - 64)*x^2 + (n^5 - 3*n^3 - 2*n^2)*x^3)*P[n - 1, x] + (512*x - (320*n^2 + 64*n)*x^2 + (8*n^4 + 16*n^3 + 88*n^2 + 16*n - 32)*x^3 - (2*n^4 + 4*n^3 + 2*n^2)*x^4)*D[P[n - 1, x], x])/(128*n - 128 - (80*n^3 - 224*n^2 + 176*n - 32)*x + (2*n^5 - 6*n^4 + 6*n^3 - 2*n^2)*x^2)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten

P(N) = {my(v = vector(N + 1)); v[1] = 0; v[2] = 3; for(n = 2, N, my(i = n + 1); v[i] = ((256*n - (160*n^3 - 288*n^2 - 192*n + 512)*x + (4*n^5 - 8*n^4 - 68*n^3 + 136*n^2 + 48*n - 64)*x^2 + (n^5 - 3*n^3 - 2*n^2)*x^3)*v[i - 1] + (512*x - (320*n^2 + 64*n)*x^2 + (8*n^4 + 16*n^3 + 88*n^2 + 16*n - 32)*x^3 - (2*n^4 + 4*n^3 + 2*n^2)*x^4)*deriv(v[i - 1], x))/(128*n - 128 - (80*n^3 - 224*n^2 + 176*n - 32)*x + (2*n^5 - 6*n^4 + 6*n^3 - 2*n^2)*x^2)); 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 multiplier sequences
• Coefficients of one sign? Every nonzero row, n ≥ 0: the coefficients of P_n have one sign
  derived from Laguerre’s theorem on multiplier sequences
• Hadamard kernel (Malo)? Rows P_n, n ≥ 0, are Hadamard kernels (preserve real-rootedness)
  derived from Laguerre’s theorem on multiplier sequences

Proof chains ? JSON

• Laguerre’s theorem on multiplier sequences [SP14; Bra15, Thm 7.1 of arXiv:1410.6601] polytool ? step ›

  • from veronese_section_2_1 of Triangle read by rows: T(n,k) is the number of ternary words of length n having k levels (n >= …?
    • Veronese sections of Pólya frequency sequences [ASW52; Edr53; AW24] polytool ? step ›

      • from Triangle read by rows: T(n,k) is the number of ternary words of length n having k levels (n >= 1, 0 <= k <= n-1). A lev…?
        • 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
        • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

          • from Triangle read by rows: T(n,k) is the number of ternary words of length n having k runs (i.e., subwords of maximal lengt…?
            • 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
            • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

              • from Triangle read by rows: T(n,k) is the number of ternary words of length n having k levels (n >= 1, 0 <= k <= n-1). A lev…?
                • ↑ Row-hypergeometric rows (multiplier sequences) (above)
                • ↑ Liu–Wang theorem (above)
                • ↑ Iterated real-rootedness preservers (above)
                • ↑ Parent-row provers of polytool (above)
            • Parent-row provers of polytool polytool ? step › direct check

Related ?

Same fingerprint ?

• A038207 → Veronese 2 (j=1) → (θ+1)²

References

1. [ASW52] Michael Aissen, I. J. Schoenberg and A. M. Whitney. On the generating functions of totally positive sequences I. Journal d’Analyse Mathématique, 2(1):93–103, 1952. doi:10.1007/BF02786970
2. [AW24] Christos A. Athanasiadis and David G. Wagner. Veronese sections and interlacing matrices of polynomials and formal power series. arXiv:2404.12989. arXiv
3. [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
4. [Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
5. [Edr53] Albert Edrei. Proof of a Conjecture of Schoenberg on the Generating Function of a Totally Positive Sequence. Canadian Journal of Mathematics, 5:86–94, 1953. doi:10.4153/CJM-1953-010-3
6. [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
7. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.