basis-map coefficients of A112227 → (θ+1)² → basis A007318

palindromicγ-positivenonnegative coefficientsonly rational roots

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

Recurrence

\(\left(1 + 2\,n + n^{2}\right)\,P_{n}(x) = \left(4 + 4\,x + 4\,n + 4\,n x + n^{2} + n^{2} x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 9 + 18\,x + 9\,x^{2}\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16Pn(1)
1918936
216484816128
32510015010025400
436180360360180361152
549294735980735294493136
6644481344224022401344448648192
781648226845365670453622686488120736
81009003600840012600126008400360090010051200
912112105445145202541030492254101452054451210121123904
101441584792023760475206652866528475202376079201584144294912
1116920281115437180836551338481561561338488365537180111542028169692224
1219625481528856056140140252252336336336336252252140140560561528825481961605632
1322531502047581900225225450450675675772200675675450450225225819002047531502253686400
1425638402688011648034944076876812812801647360164736012812807687683494401164802688038402568388608
15289462434680161840525980126235223143123306160371943033061602314312126235252598016184034680462428918939904
Technical details
Node id
n-306608f35882b9cc · 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:   9,   18,    9;
   2:  16,   48,   48,    16;
   3:  25,  100,  150,   100,    25;
   4:  36,  180,  360,   360,   180,    36;
   5:  49,  294,  735,   980,   735,   294,    49;
   6:  64,  448, 1344,  2240,  2240,  1344,   448,    64;
   7:  81,  648, 2268,  4536,  5670,  4536,  2268,   648,    81;
   8: 100,  900, 3600,  8400, 12600, 12600,  8400,  3600,   900,  100;
   9: 121, 1210, 5445, 14520, 25410, 30492, 25410, 14520,  5445, 1210,  121;
  10: 144, 1584, 7920, 23760, 47520, 66528, 66528, 47520, 23760, 7920, 1584, 144;
%F Formula
The row polynomials satisfy (n^2+2*n+1)*P(n,x) = (n^2+4*n+4+(n^2+4*n+4)*x)*P(n-1,x) for n >= 2, with P(1,x) = 9 + 18*x + 9*x^2.
%t Mathematica
P[1, x_] := 9 + 18*x + 9*x^2;
P[n_, x_] := P[n, x] = Expand[Together[((n^2 + 4*n + 4 + (n^2 + 4*n + 4)*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 + 18*x + 9*x^2; for(n = 2, N, my(i = n); v[i] = ((n^2 + 4*n + 4 + (n^2 + 4*n + 4)*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.