basis-map coefficients of A112227 → basis A013609

nonnegative coefficients only rational roots

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

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

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16Pn(1)
11449
21612827
31824321681
411040808032243
51126016024019264729
6114842805606724481282187
711611244811201792179210242566561
81181446722016403253764608230451219683
9120180960336080641344015360115205120102459049
10122220132052801478429568422404224028160112642048177147
1112426417607920253445913610137612672011264067584245764096531441
12126312228811440411841098242196483294723660802928641597445324881921594323
131283642912160166406419219243929676876810250241025024745472372736114688163844782969
1413042036402184096096320320823680164736025625603075072279552018636808601602457603276814348907
15132480448029120139776512512146432032947205857280820019289456647454720458752019660805242886553643046721

Computed in your browser ?

Technical details
Node id
n-fdb3be84f583ed95 · revision 1 · JSON
Definition source
derived:basis_map_A013609
Fingerprint
f6-11aec07ce60b6d61

Observed on the stored rows ?

  • Degrees: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 (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): yes

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,  4,   4;
   2: 1,  6,  12,    8;
   3: 1,  8,  24,   32,   16;
   4: 1, 10,  40,   80,   80,    32;
   5: 1, 12,  60,  160,  240,   192,    64;
   6: 1, 14,  84,  280,  560,   672,   448,   128;
   7: 1, 16, 112,  448, 1120,  1792,  1792,  1024,   256;
   8: 1, 18, 144,  672, 2016,  4032,  5376,  4608,  2304,   512;
   9: 1, 20, 180,  960, 3360,  8064, 13440, 15360, 11520,  5120,  1024;
  10: 1, 22, 220, 1320, 5280, 14784, 29568, 42240, 42240, 28160, 11264, 2048;
%F Formula
The row polynomials satisfy P(n,x) = (1+2*x)*P(n-1,x) for n >= 2, with P(1,x) = 1 + 4*x + 4*x^2.
%t Mathematica
P[1, x_] := 1 + 4*x + 4*x^2;
P[n_, x_] := P[n, x] = Expand[(1 + 2*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 + 4*x + 4*x^2; for(n = 2, N, my(i = n); v[i] = (1 + 2*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-7bee75fc05394bb8
  • 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-7bee75fc05394bb8
  • 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-7bee75fc05394bb8

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

Same fingerprint (67)

Equal up to content, sign, reversal and a small index shift.