Real-rooted atlas

A120909 → basis A013610 → (θ+1)²

nonnegative coefficients

Proved for all n all roots real, in (−∞, 0]coefficients of one signHadamard kernelinterlacing (weak)

Recurrence

\(\left(1 - 2\,x + 6\,n x + 4\,n^{2} x^{2}\right)\,P_{n}(x) = \left(3 + 18\,x + 36\,x^{2} + 24\,x^{3} + 18\,n x + 60\,n x^{2} + 48\,n x^{3} + 12\,n^{2} x^{2} + 24\,n^{2} x^{3}\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 3\)

Rows ?

nx0x1x2x3x4x5x6x7Pn(1)
033
197281
2274329721431
381194487481036821141
424377765248812441697200282123
57292916026244093312014580008398083523257
62187104976118098055987201312200015116544685843241983839
765613674164960116293932809185400015872371214402707253747712483079869

All 15 rows

Technical details
Node id
n-155438c5dea0b978 · revision 0 · JSON
Definition source
derived:theta_plus_one_squared
Fingerprint
f6-181bf1738e48841f

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 0)
  • 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

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 0, …, ascending powers of x
%e Example
Triangle begins:
  0:     3;
  1:     9,      72;
  2:    27,     432,      972;
  3:    81,    1944,     8748,     10368;
  4:   243,    7776,    52488,    124416,      97200;
  5:   729,   29160,   262440,    933120,    1458000,     839808;
  6:  2187,  104976,  1180980,   5598720,   13122000,   15116544,     6858432;
  7:  6561,  367416,  4960116,  29393280,   91854000,  158723712,   144027072,    53747712;
  8: 19683, 1259712, 19840464, 141087744,  551124000, 1269789696,  1728324864,  1289945088,   408146688;
  9: 59049, 4251528, 76527504, 634894848, 2976069600, 8571080448, 15554923776, 17414258688, 11019960576, 3023308800;
%F Formula
The row polynomials satisfy (1+(6*n-2)*x+4*n^2*x^2)*P(n,x) = (3+(18*n+18)*x+(12*n^2+60*n+36)*x^2+(24*n^2+48*n+24)*x^3)*P(n-1,x) for n >= 1, with P(0,x) = 3.
%t Mathematica
P[0, x_] := 3;
P[n_, x_] := P[n, x] = Expand[Together[((3 + (18*n + 18)*x + (12*n^2 + 60*n + 36)*x^2 + (24*n^2 + 48*n + 24)*x^3)*P[n - 1, x])/(1 + (6*n - 2)*x + 4*n^2*x^2)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N + 1)); v[1] = 3; for(n = 1, N, my(i = n + 1); v[i] = ((3 + (18*n + 18)*x + (12*n^2 + 60*n + 36)*x^2 + (24*n^2 + 48*n + 24)*x^3)*v[i - 1])/(1 + (6*n - 2)*x + 4*n^2*x^2)); 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)

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