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

nonnegative coefficientsonly rational roots

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16Pn(1)
1912425
22754368125
3812162169616625
42438101080720240323125
572929164860432021605766415625
62187102062041222680151206048134412878125
7656134992816481088649072048384161283072256390625
8196831180983149284898884898883265921451524147269125121953125
959049393660118098020995202449440195955210886404147201036801536010249765625
10177147129907843302608660520115473601077753671850243421440114048025344033792204848828125
115314414251528155889363464208051963120554273284311014424634368102643203041280608256737284096244140625
121594323138174665526986413510411222517352027020822424018508816012339280061696296524807907328143769615974481921220703125
134782969446410441934445245158520649457287841260971712126097171296074035256043187224908083283026944201277443354624344064163846103515625
141434890714348907066961566019344452403868890480567437270463048585605404164480360277632018681062407472424962264371205031936077414407372803276830517578125
1543046721459165024229582512071425670401547556192024760899072302633210882882221056021616657920128098713605977939968217379635260383232012386304017694720157286465536152587890625
Technical details
Node id
n-98b538591e795174 · revision 0 · JSON
Definition source
derived:shift_x_plus_one
Fingerprint
f6-f06e51c139cfae05

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,      12,       4;
   2:     27,      54,      36,       8;
   3:     81,     216,     216,      96,       16;
   4:    243,     810,    1080,     720,      240,       32;
   5:    729,    2916,    4860,    4320,     2160,      576,      64;
   6:   2187,   10206,   20412,   22680,    15120,     6048,    1344,     128;
   7:   6561,   34992,   81648,  108864,    90720,    48384,   16128,    3072,     256;
   8:  19683,  118098,  314928,  489888,   489888,   326592,  145152,   41472,    6912,    512;
   9:  59049,  393660, 1180980, 2099520,  2449440,  1959552, 1088640,  414720,  103680,  15360,  1024;
  10: 177147, 1299078, 4330260, 8660520, 11547360, 10777536, 7185024, 3421440, 1140480, 253440, 33792, 2048;
%F Formula
The row polynomials satisfy P(n,x) = (3+2*x)*P(n-1,x) for n >= 2, with P(1,x) = 9 + 12*x + 4*x^2.
%t Mathematica
P[1, x_] := 9 + 12*x + 4*x^2;
P[n_, x_] := P[n, x] = Expand[(3 + 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] = 9 + 12*x + 4*x^2; for(n = 2, N, my(i = n); v[i] = (3 + 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.