basis-map coefficients of A112227 → θ+1 → x ↦ x+1

palindromicγ-positivenonnegative coefficientsonly rational roots

Proved for all n all roots real, in (−∞, −1]coefficients of one signHadamard kernelinterlacing (weak)

Recurrence

\(\left(1 + n\right)\,P_{n}(x) = \left(2 + 2\,x + n + n x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 3 + 6\,x + 3\,x^{2}\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9Pn(1)
136312
241212432
35203020580
46306060306192
5742105140105427448
68561682802801685681024
79722525046305042527292304
810903608401260126084036090105120
Technical details
Node id
n-f1e6146737e570cf · revision 0 · JSON
Definition source
derived:shift_x_plus_one
Fingerprint
f6-77a7ed3b1d5f257e

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: yes
  • γ-positive (gamma_positive): yes
  • Nonnegative coefficients (nonn): yes
  • Only rational roots (rr_by_factors: every nonzero row is a product of linear factors over ℚ): yes

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 1, …, ascending powers of x
%e Example
Triangle begins:
   1:  3,   6,   3;
   2:  4,  12,  12,    4;
   3:  5,  20,  30,   20,    5;
   4:  6,  30,  60,   60,   30,    6;
   5:  7,  42, 105,  140,  105,   42,    7;
   6:  8,  56, 168,  280,  280,  168,   56,    8;
   7:  9,  72, 252,  504,  630,  504,  252,   72,    9;
   8: 10,  90, 360,  840, 1260, 1260,  840,  360,   90,  10;
   9: 11, 110, 495, 1320, 2310, 2772, 2310, 1320,  495, 110,  11;
  10: 12, 132, 660, 1980, 3960, 5544, 5544, 3960, 1980, 660, 132, 12;
%F Formula
The row polynomials satisfy (n+1)*P(n,x) = (n+2+(n+2)*x)*P(n-1,x) for n >= 2, with P(1,x) = 3 + 6*x + 3*x^2.
%t Mathematica
P[1, x_] := 3 + 6*x + 3*x^2;
P[n_, x_] := P[n, x] = Expand[Together[((n + 2 + (n + 2)*x)*P[n - 1, x])/(n + 1)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N)); v[1] = 3 + 6*x + 3*x^2; for(n = 2, N, my(i = n); v[i] = ((n + 2 + (n + 2)*x)*v[i - 1])/(n + 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)

polytool c48629374597

Properties

Proof chains ? JSON

Same fingerprint ?

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. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.