basis-map coefficients of A112227 → (θ+1)² → basis A013610

nonnegative coefficientsonly rational roots

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

Recurrence

\(\left(1 + 2\,n + n^{2}\right)\,P_{n}(x) = \left(4 + 12\,x + 4\,n + 12\,n x + n^{2} + 3\,n^{2} x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 9 + 54\,x + 81\,x^{2}\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9Pn(1)
195481144
2161444324321024
3253001350270020256400
4365403240972014580874836864
549882661526460595357144235721200704
664134412096604801814403265923265921399681048576
7811944204121224724592701102248165337214171765314415308416
810027003240022680010206003061800612360078732005904900196830026214400
Technical details
Node id
n-77ad33e787d11fa8 · revision 0 · JSON
Definition source
derived:basis_map_A013610
Fingerprint
f6-f9762973ec1089d7

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:   9,   54,    81;
   2:  16,  144,   432,    432;
   3:  25,  300,  1350,   2700,    2025;
   4:  36,  540,  3240,   9720,   14580,     8748;
   5:  49,  882,  6615,  26460,   59535,    71442,    35721;
   6:  64, 1344, 12096,  60480,  181440,   326592,   326592,    139968;
   7:  81, 1944, 20412, 122472,  459270,  1102248,  1653372,   1417176,    531441;
   8: 100, 2700, 32400, 226800, 1020600,  3061800,  6123600,   7873200,   5904900,   1968300;
   9: 121, 3630, 49005, 392040, 2058210,  7409556, 18523890,  31755240,  35724645,  23816430,  7144929;
  10: 144, 4752, 71280, 641520, 3849120, 16166304, 48498912, 103926240, 155889360, 155889360, 93533616, 25509168;
%F Formula
The row polynomials satisfy (n^2+2*n+1)*P(n,x) = (n^2+4*n+4+(3*n^2+12*n+12)*x)*P(n-1,x) for n >= 2, with P(1,x) = 9 + 54*x + 81*x^2.
%t Mathematica
P[1, x_] := 9 + 54*x + 81*x^2;
P[n_, x_] := P[n, x] = Expand[Together[((n^2 + 4*n + 4 + (3*n^2 + 12*n + 12)*x)*P[n - 1, x])/(n^2 + 2*n + 1)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N)); v[1] = 9 + 54*x + 81*x^2; for(n = 2, N, my(i = n); v[i] = ((n^2 + 4*n + 4 + (3*n^2 + 12*n + 12)*x)*v[i - 1])/(n^2 + 2*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.