basis-map coefficients of A112227 → x ↦ x+1 → basis A013609

palindromicγ-positivenonnegative coefficientsonly rational roots

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

Recurrence

\(P_{n}(x) = \left(2 + 2\,x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 4 + 8\,x + 4\,x^{2}\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16Pn(1)
148416
282424864
31664966416256
432160320320160321024
5643849601280960384644096
6128896268844804480268889612816384
7256204871681433617920143367168204825665536
851246081843243008645126451243008184324608512262144
910241024046080122880215040258048215040122880460801024010241048576
102048225281126403379206758409461769461766758403379201126402252820484194304
114096491522703369011202027520324403237847043244032202752090112027033649152409616777216
128192106496638976234291258572801054310414057472140574721054310458572802342912638976106496819267108864
131638422937614909445963776164003843280076849201152562298884920115232800768164003845963776149094422937616384268435456
143276849152034406401490944044728320984023041640038402108620802108620801640038409840230444728320149094403440640491520327681073741824
156553610485767864320367001601192755202862612485248122887497318408434483207497318405248122882862612481192755203670016078643201048576655364294967296
Technical details
Node id
n-4d4af5f206880e6d · revision 0 · JSON
Definition source
derived:basis_map_A013609
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:    4,     8,      4;
   2:    8,    24,     24,      8;
   3:   16,    64,     96,     64,     16;
   4:   32,   160,    320,    320,    160,     32;
   5:   64,   384,    960,   1280,    960,    384,     64;
   6:  128,   896,   2688,   4480,   4480,   2688,    896,    128;
   7:  256,  2048,   7168,  14336,  17920,  14336,   7168,   2048,    256;
   8:  512,  4608,  18432,  43008,  64512,  64512,  43008,  18432,   4608,    512;
   9: 1024, 10240,  46080, 122880, 215040, 258048, 215040, 122880,  46080,  10240,  1024;
  10: 2048, 22528, 112640, 337920, 675840, 946176, 946176, 675840, 337920, 112640, 22528, 2048;
%F Formula
The row polynomials satisfy P(n,x) = (2+2*x)*P(n-1,x) for n >= 2, with P(1,x) = 4 + 8*x + 4*x^2.
%t Mathematica
P[1, x_] := 4 + 8*x + 4*x^2;
P[n_, x_] := P[n, x] = Expand[(2 + 2*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] = 4 + 8*x + 4*x^2; for(n = 2, N, my(i = n); v[i] = (2 + 2*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.