basis-map coefficients of A112227 → (θ+1)² → basis A013611

nonnegative coefficientsonly rational roots

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

Recurrence

\(\left(1 + 2\,n + n^{2}\right)\,P_{n}(x) = \left(4 + 16\,x + 4\,n + 16\,n x + n^{2} + 4\,n^{2} x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 9 + 72\,x + 144\,x^{2}\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9Pn(1)
1972144225
21619276810242000
32540024006400640015625
4367205760230404608036864112500
54911761176062720188160301056200704765625
6641792215041433605734401376256183500810485765000000
78125923628829030414515204644864928972810616832530841631640625
810036005760053760032256001290240034406400589824005898240026214400195312500
Technical details
Node id
n-162098c126ccbc3b · revision 0 · JSON
Definition source
derived:basis_map_A013611
Fingerprint
f6-03d7b8417365c509

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,   72,    144;
   2:  16,  192,    768,    1024;
   3:  25,  400,   2400,    6400,     6400;
   4:  36,  720,   5760,   23040,    46080,    36864;
   5:  49, 1176,  11760,   62720,   188160,   301056,    200704;
   6:  64, 1792,  21504,  143360,   573440,  1376256,   1835008,   1048576;
   7:  81, 2592,  36288,  290304,  1451520,  4644864,   9289728,  10616832,    5308416;
   8: 100, 3600,  57600,  537600,  3225600, 12902400,  34406400,  58982400,   58982400,   26214400;
   9: 121, 4840,  87120,  929280,  6504960, 31223808, 104079360, 237895680,  356843520,  317194240,  126877696;
  10: 144, 6336, 126720, 1520640, 12165120, 68124672, 272498688, 778567680, 1557135360, 2076180480, 1660944384, 603979776;
%F Formula
The row polynomials satisfy (n^2+2*n+1)*P(n,x) = (n^2+4*n+4+(4*n^2+16*n+16)*x)*P(n-1,x) for n >= 2, with P(1,x) = 9 + 72*x + 144*x^2.
%t Mathematica
P[1, x_] := 9 + 72*x + 144*x^2;
P[n_, x_] := P[n, x] = Expand[Together[((n^2 + 4*n + 4 + (4*n^2 + 16*n + 16)*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 + 72*x + 144*x^2; for(n = 2, N, my(i = n); v[i] = ((n^2 + 4*n + 4 + (4*n^2 + 16*n + 16)*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.