A099097 → basis A013611

nonnegative coefficients

Proved for all n: all roots real, in (−∞, 0] · coefficients of one sign · Hadamard kernel what this means

Recurrence
\(P_{n}(x) = \left(1 + 4\,x\right)\,P_{n-2}(x) + \left(3 + 12\,x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 1\)
\(P_{2}(x) = 3 + 12\,x\)

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
111
231215
31076144230
433372139217283525
510916289088224642073654025
6360669649680183744338688248832828000
7118926472244992120620833315844893696298598412690125
839271018201129104694099225542912562636806867763235831808194491875

Computed in your browser ?

Technical details
Node id
n-a6e4c21559f1b253 · revision 1 · JSON
Definition source
derived:basis_map_A013611
Fingerprint
f6-0fb6267fe8136ac2

Observed on the stored rows ?

  • Degrees: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 (affine: slope 1, intercept -1)
  • Palindromic rows: no
  • γ-positive (gamma_positive): no
  • Nonnegative coefficients (nonn): yes
  • Only rational roots (rr_by_factors: every nonzero row is a product of linear factors over ℚ): no

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.

The atlas's own rows: n = 1, …, ascending powers of x
%e Example
Triangle begins:
   1:     1;
   2:     3,      12;
   3:    10,      76,      144;
   4:    33,     372,     1392,      1728;
   5:   109,    1628,     9088,     22464,     20736;
   6:   360,    6696,    49680,    183744,    338688,     248832;
   7:  1189,   26472,   244992,   1206208,   3331584,    4893696,    2985984;
   8:  3927,  101820,  1129104,   6940992,  25542912,   56263680,   68677632,    35831808;
   9: 12970,  383812,  4960032,  36558400, 168077056,  493526016,  903757824,   943570944,   429981696;
  10: 42837, 1424604, 21022224, 180652992, 996238848, 3655938048, 8927318016, 13986349056, 12756123648, 5159780352;
%F Formula
The row polynomials satisfy P(n,x) = (1+4*x)*P(n-2,x) + (3+12*x)*P(n-1,x) for n >= 3, with P(1,x) = 1, P(2,x) = 3 + 12*x.
%t Mathematica
P[1, x_] := 1;
P[2, x_] := 3 + 12*x;
P[n_, x_] := P[n, x] = Expand[(1 + 4*x)*P[n - 2, x] + (3 + 12*x)*P[n - 1, x]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N)); v[1] = 1; v[2] = 3 + 12*x; for(n = 3, N, my(i = n); v[i] = (1 + 4*x)*v[i - 2] + (3 + 12*x)*v[i - 1]); 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)

Generated with polytool c48629374597.

Proved properties

  • Real-rooted. Every row P_n, n >= 1, is zero or real-rooted with all roots in (-inf, 0]
    Every polynomial of the sequence has only real roots, inside the stated interval.
    by the cited steps: e-ce8b1eb4dfdacda9
  • Coefficients of one sign. Every nonzero row, n >= 1: the coefficients of P_n have one sign
    All coefficients of each polynomial have the same sign (after x -> -x when alternating).
    derived from the cited steps by a stated theorem: e-ce8b1eb4dfdacda9
  • Hadamard kernel (Malo). Rows P_n, n >= 1, are Hadamard kernels (preserve real-rootedness)
    Multiplying the coefficients of any real-rooted polynomial termwise by those of a row (Hadamard product) gives a real-rooted polynomial again.
    derived from the cited steps by a stated theorem: e-ce8b1eb4dfdacda9

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

No candidate equalities or related sequences.

References

  1. [MW08] Shi-Mei Ma and Yi Wang. q-Eulerian polynomials and polynomials with only real zeros. The Electronic Journal of Combinatorics, 15(1):Research Paper 17, January 2008. doi:10.37236/741