basis-map coefficients of A127647 → x ↦ x/(x+1)

nonnegative coefficientsonly rational roots

Proved for all n all roots real, in [−1, 0]coefficients of one signHadamard kernel

Recurrence

\(\left(1 + 2\,x + x^{2}\right)\,P_{n}(x) = \left(1 + 6\,x + 13\,x^{2} + 12\,x^{3} + 4\,x^{4}\right)\,P_{n-2}(x) + \left(1 + 4\,x + 5\,x^{2} + 2\,x^{3}\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 1\)
\(P_{1}(x) = 1 + 2\,x\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14Pn(1)
011
1123
228818
3318362481
454012016080405
58803206406402561944
6131567802080312024968329477
7212941764588011760141129408268845927
834544380815232380806092860928348168704223074
955990792036960110880221760295680253440126720281601082565
108917801602085440299040717696119616013670401025280455680911365255361
1114431683168019008076032021288964257792608256060825604055040162201629491225509168
122335592615124100801845360590515213778688236206082952576026245120157470725726208954368123825753
133779802117624862576431288015526368414036488280729612421094413801216011040972860223488200744963088384601059771
146101708022204017763209769760390790401172371202679705604689484806252646406252646404547379202273689606995968099942402917611090
Technical details
Node id
n-e621a5e3fc665a4e · revision 0 · JSON
Definition source
derived:mobius_x_over_x_plus_one
Fingerprint
f6-11aec07ce60b6d61

Observed on the stored rows ?

  • Degrees: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 (affine: slope 1, intercept 0)
  • 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 = 0, …, ascending powers of x
%e Example
Triangle begins:
  0:  1;
  1:  1,   2;
  2:  2,   8,    8;
  3:  3,  18,   36,    24;
  4:  5,  40,  120,   160,     80;
  5:  8,  80,  320,   640,    640,    256;
  6: 13, 156,  780,  2080,   3120,   2496,    832;
  7: 21, 294, 1764,  5880,  11760,  14112,   9408,   2688;
  8: 34, 544, 3808, 15232,  38080,  60928,  60928,  34816,   8704;
  9: 55, 990, 7920, 36960, 110880, 221760, 295680, 253440, 126720, 28160;
%F Formula
The row polynomials satisfy (1+2*x+x^2)*P(n,x) = (1+6*x+13*x^2+12*x^3+4*x^4)*P(n-2,x) + (1+4*x+5*x^2+2*x^3)*P(n-1,x) for n >= 2, with P(0,x) = 1, P(1,x) = 1 + 2*x.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 1 + 2*x;
P[n_, x_] := P[n, x] = Expand[Together[((1 + 6*x + 13*x^2 + 12*x^3 + 4*x^4)*P[n - 2, x] + (1 + 4*x + 5*x^2 + 2*x^3)*P[n - 1, x])/(1 + 2*x + x^2)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N + 1)); v[1] = 1; v[2] = 1 + 2*x; for(n = 2, N, my(i = n + 1); v[i] = ((1 + 6*x + 13*x^2 + 12*x^3 + 4*x^4)*v[i - 2] + (1 + 4*x + 5*x^2 + 2*x^3)*v[i - 1])/(1 + 2*x + x^2)); v};
row(n, p) = {my(c = Vecrev(p)); c};
T(N) = {my(v = P(N)); concat(vector(#v, i, row(i - 1, v[i])))};
T(9)

polytool c48629374597

Properties

Proof chains ? JSON

Same fingerprint ?

References

  1. [Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
  2. [SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.