Real-rooted atlas

basis-map coefficients of A112227 → basis A013611 → x ↦ x+1

nonnegative coefficientsonly rational roots

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

Recurrence

\(P_{n}(x) = \left(5 + 4\,x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 25 + 40\,x + 16\,x^{2}\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9Pn(1)
125401681
212530024064729
36252000240012802566561
431251250020000160006400102459049
5156257500015000016000096000307204096531441
678125437500105000014000001120000537600143360163844782969
7390625250000070000001120000011200000716800028672006553606553643046721
819531251406250045000000840000001008000008064000043008000147456002949120262144387420489

All 15 rows

Technical details
Node id
n-03ac2a4394de29ac · revision 0 · JSON
Definition source
derived:shift_x_plus_one
Fingerprint
f6-6b726760bd05165a

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

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 1, …, ascending powers of x
%e Example
Triangle begins:
   1:       25,        40,         16;
   2:      125,       300,        240,         64;
   3:      625,      2000,       2400,       1280,        256;
   4:     3125,     12500,      20000,      16000,       6400,       1024;
   5:    15625,     75000,     150000,     160000,      96000,      30720,       4096;
   6:    78125,    437500,    1050000,    1400000,    1120000,     537600,     143360,      16384;
   7:   390625,   2500000,    7000000,   11200000,   11200000,    7168000,    2867200,     655360,      65536;
   8:  1953125,  14062500,   45000000,   84000000,  100800000,   80640000,   43008000,   14745600,    2949120,    262144;
   9:  9765625,  78125000,  281250000,  600000000,  840000000,  806400000,  537600000,  245760000,   73728000,  13107200,  1048576;
  10: 48828125, 429687500, 1718750000, 4125000000, 6600000000, 7392000000, 5913600000, 3379200000, 1351680000, 360448000, 57671680, 4194304;
%F Formula
The row polynomials satisfy P(n,x) = (5+4*x)*P(n-1,x) for n >= 2, with P(1,x) = 25 + 40*x + 16*x^2.
%t Mathematica
P[1, x_] := 25 + 40*x + 16*x^2;
P[n_, x_] := P[n, x] = Expand[(5 + 4*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] = 25 + 40*x + 16*x^2; for(n = 2, N, my(i = n); v[i] = (5 + 4*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)

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.