A028326 → basis A013610 → x ↦ x/(x+1)

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Submission text ?

Triangle begins:
  0:    2;
  1:    4,    10;
  2:    8,    40,     50;
  3:   16,   120,    300,     250;
  4:   32,   320,   1200,    2000,    1250;
  5:   64,   800,   4000,   10000,   12500,     6250;
  6:  128,  1920,  12000,   40000,   75000,    75000,    31250;
  7:  256,  4480,  33600,  140000,  350000,   525000,   437500,   156250;
  8:  512, 10240,  89600,  448000, 1400000,  2800000,  3500000,  2500000,   781250;
  9: 1024, 23040, 230400, 1344000, 5040000, 12600000, 21000000, 22500000, 14062500, 3906250;

The row polynomials satisfy (1+x)*P(n,x) = (2+7*x+5*x^2)*P(n-1,x) for n >= 1, with P(0,x) = 2.

P[0, x_] := 2;
P[n_, x_] := P[n, x] = Expand[Together[((2 + 7*x + 5*x^2)*P[n - 1, x])/(1 + x)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten

P(N) = {my(v = vector(N + 1)); v[1] = 2; for(n = 1, N, my(i = n + 1); v[i] = ((2 + 7*x + 5*x^2)*v[i - 1])/(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 [-1, 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_A013610 of Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).?
    • Geometric basis map (elementary) polytool ? step ›

      • from Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).?
        • Liu–Wang theorem [LW07, Thm 2.1, Cor 2.4] ? 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
        • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

          • from Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).?
            • ↑ Liu–Wang theorem (above)
            • ↑ Row-hypergeometric rows (multiplier sequences) (above)
            • 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
        • ↑ Parent-row provers of polytool (above)
        • ↑ Iterated real-rootedness preservers (above)
    • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

      • from shift_x_plus_one of Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).?
        • Affine, reversal and Möbius substitutions (elementary) polytool ? step ›

          • from Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).?
            • ↑ Liu–Wang theorem (above)
            • ↑ Row-hypergeometric rows (multiplier sequences) (above)
            • ↑ Affine, reversal and Möbius substitutions (elementary) (above)
            • ↑ Parent-row provers of polytool (above)
            • ↑ Iterated real-rootedness preservers (above)
        • Geometric basis map (elementary) polytool ? step ›

          • from Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).?
            • ↑ Liu–Wang theorem (above)
            • ↑ Row-hypergeometric rows (multiplier sequences) (above)
            • ↑ Affine, reversal and Möbius substitutions (elementary) (above)
            • ↑ Parent-row provers of polytool (above)
            • ↑ Iterated real-rootedness preservers (above)

Related ?

Same fingerprint ?

• A038329 → basis A013609
• A085880 → basis A013610 → x ↦ x/(x+1)
• A013622 → basis A013611 → D
• A038231 → D → basis A013609
• A120910 → basis A013609 → basis A007318
• A038291 → basis A013611 → reverse
• A178822 → basis A013610 → x ↦ x/(x+1)
• A196347 → basis A013610 → x ↦ x/(x+1)
• A038334 → x ↦ x+1
• A038221 → basis A013610 → x ↦ x/(x+1)
• A178820 → basis A013610 → x ↦ x/(x+1)
• A038334 → x ↦ x+1 → reverse
• A038220 → basis A007318
• A038334 → x ↦ x+1 → D
• A038291 → basis A013611 → D
• A038329 → basis A013609 → D
• A156992 → basis A013610 → x ↦ x/(x+1)
• A013620 → x ↦ x/(x+1)
• A038327 → basis A013609 → basis A013610
• A178821 → basis A013610 → x ↦ x/(x+1)
• A013612 → basis A013610
• A013622 → basis A013611
• A038208 → basis A013610 → x ↦ x/(x+1)
• A038220 → basis A007318 → D
• A013622 → basis A013611 → reverse
• A038338 → basis A013610 → x ↦ x/(x+1)
• A013612 → basis A013610 → D
• A038220 → basis A007318 → reverse
• A038291 → 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.