basis-map coefficients of A112227 → x ↦ x+1 → basis A007318

nonnegative coefficientsonly rational roots

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16Pn(1)
14419
28126127
31632248181
432808040101243
56419224016060121729
6128448672560280841412187
725610241792179211204481121616561
85122304460853764032201667214418119683
9102451201152015360134408064336096018020159049
10204811264281604224042240295681478452801320220221177147
1140962457667584112640126720101376591362534479201760264241531441
12819253248159744292864366080329472219648109824411841144022883122611594323
131638411468837273674547210250241025024768768439296192192640641601629123642814782969
1432768245760860160186368027955203075072256256016473608236803203209609621840364042030114348907
15655365242881966080458752074547208945664820019258572803294720146432051251213977629120448048032143046721
Technical details
Node id
n-35019173dc21748d · revision 0 · JSON
Definition source
derived:shift_x_plus_one
Fingerprint
f6-11aec07ce60b6d61

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:    4,     4,     1;
   2:    8,    12,     6,     1;
   3:   16,    32,    24,     8,     1;
   4:   32,    80,    80,    40,    10,     1;
   5:   64,   192,   240,   160,    60,    12,     1;
   6:  128,   448,   672,   560,   280,    84,    14,    1;
   7:  256,  1024,  1792,  1792,  1120,   448,   112,   16,    1;
   8:  512,  2304,  4608,  5376,  4032,  2016,   672,  144,   18,   1;
   9: 1024,  5120, 11520, 15360, 13440,  8064,  3360,  960,  180,  20,  1;
  10: 2048, 11264, 28160, 42240, 42240, 29568, 14784, 5280, 1320, 220, 22, 1;
%F Formula
The row polynomials satisfy P(n,x) = (2+x)*P(n-1,x) for n >= 2, with P(1,x) = 4 + 4*x + x^2.
%t Mathematica
P[1, x_] := 4 + 4*x + x^2;
P[n_, x_] := P[n, x] = Expand[(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 + 4*x + x^2; for(n = 2, N, my(i = n); v[i] = (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.