A257623 → Pₙ + Pₙ₊₁

OEIS matches ?

No OEIS matches.

OEIS submission text ?

Fields to paste into an OEIS submission: the example %e, the formula %F and programs %t (Mathematica) and %o (PARI/GP) that list the same rows. For an OEIS link the row numbers, the offset and the orientation are those of the entry, as matched; the matched terms were compared with the published ones, which identifies the node with the entry on a finite prefix, not for every n. The PARI/GP program is not machine-checked here.

Triangle begins:
  0:     4,          3;
  1:    12,         51,            9;
  2:    36,        549,          510,            27;
  3:   108,       4995,        13527,          4521,             81;
  4:   324,      42309,       263256,        254724,          37896,            243;
  5:   972,     347139,      4372965,       9258510,        4160550,         309567,            729;
  6:  2916,    2807973,     66379362,     265980225,      261094680,       62565951,        2499378,          2187;
  7:  8748,   22570947,    954048195,    6625652511,    12077681415,     6430937193,      894290217,      20074485,         6561;
  8: 26244,  180932805,  13247829276,  150434052498,   462020083128,   456568054224,   144957163500,   12376110006,    160867068,      19683;
  9: 78732, 1448689347, 179901529713, 3206771499612, 15558942241548, 25661364298506, 15252808239822, 3075062165388, 167706352512, 1287848523, 59049;

The row polynomials satisfy P(n,x) = (3+(5*n-7)*x)*P(n-2,x) + (5*x-5*x^2)*d/dx P(n-2,x) + (2+(5*n+3)*x)*P(n-1,x) + (5*x-5*x^2)*d/dx P(n-1,x) for n >= 2, with P(0,x) = 4 + 3*x, P(1,x) = 12 + 51*x + 9*x^2.

P[0, x_] := 4 + 3*x;
P[1, x_] := 12 + 51*x + 9*x^2;
P[n_, x_] := P[n, x] = Expand[(3 + (5*n - 7)*x)*P[n - 2, x] + (5*x - 5*x^2)*D[P[n - 2, x], x] + (2 + (5*n + 3)*x)*P[n - 1, x] + (5*x - 5*x^2)*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] = 4 + 3*x; v[2] = 12 + 51*x + 9*x^2; for(n = 2, N, my(i = n + 1); v[i] = (3 + (5*n - 7)*x)*v[i - 2] + (5*x - 5*x^2)*deriv(v[i - 2], x) + (2 + (5*n + 3)*x)*v[i - 1] + (5*x - 5*x^2)*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)

Proved properties

• Real-rooted. Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, +inf)
  Every polynomial of the sequence has only real roots, inside the stated interval.
  by the cited steps: e-fccdbe2b7271fb46

Proof chains

1 incoming proof step. Each step is expanded back to the roots of the proof DAG, the theorem checks of a node's own rule. JSON

• obreschkoff_combination e-fccdbe2b7271fb46

  Hermite–Kakeya–Obreschkoff theorem [Obr63; Fis06, Thm 1.43] ?

  • premise (sequence): Triangle read by rows: T(n,k) = t(n-k, k), where t(n,m) = f(m)*t(n-1,m) + f(n)*t(n,m-1) and f(n) = 5*n + 3.
    uses: Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, +inf)
    • theorem_check liu_wang e-d9277c75939e8d2f root: theorem check

      Liu–Wang theorem [LW07, Thm 2.1, Cor 2.4] ?

  • premise (sequence): Triangle read by rows: T(n,k) = t(n-k, k), where t(n,m) = f(m)*t(n-1,m) + f(n)*t(n,m-1) and f(n) = 5*n + 3.
    uses: Rows P_(m-1), P_m interlace (weak, unordered) for every m >= 1
    no recorded property covers this requirement

Related sequences ?

No candidate equalities or related sequences.

References

1. [Fis06] Steve Fisk. Polynomials, roots, and interlacing. arXiv:math/0612833. arXiv
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. [Obr63] Nikola Obreschkoff. Verteilung und berechnung der nullstellen reeller polynome. Hochschulbücher für mathematik, VEB Deutscher Verlag der Wissenschaften, 1963.