A125662 → θ+1

nonnegative coefficients

Proved for all n: all roots real, in (−∞, 0] · coefficients of one sign · interlacing (weak) · Hadamard kernel what this means

Recurrence

\(\left(-20\,n - 6\,n x + 2\,n^{3} x^{2}\right)\,P_{n}(x) = \left(-30 - 24\,x - 6\,x^{2} - 30\,n - 29\,n x - 6\,n x^{2} + n x^{3} - 5\,n^{2} x + 3\,n^{2} x^{2} + 2\,n^{2} x^{3} + 3\,n^{3} x^{2} + n^{3} x^{3}\right)\,P_{n-1}(x) + \left(-25 - 45\,x - 23\,x^{2} - 3\,x^{3} + 5\,n x^{2} + 6\,n x^{3} + n x^{4} + 5\,n^{2} x^{2} + 6\,n^{2} x^{3} + n^{2} x^{4}\right)\,P_{n-1}'(x)\)

\(P_{0}(x) = 1\)

Rows ?

n	x⁰	x¹	x²	x³	x⁴	x⁵	x⁶	x⁷	P_n(1)
0	1								1
1	3	2							5
2	8	12	3						23
3	21	50	27	4					102
4	55	180	153	48	5				441
5	144	600	702	344	75	6			1871
6	377	1908	2853	1920	650	108	7		7823
7	987	5878	10719	9220	4275	1098	147	8	32332

Show all 15 stored rows

Computed in your browser ?

Technical details

Node id: n-d01ecaaeb3718f4e · revision 1 · JSON
Definition source: derived:theta_plus_one
Fingerprint: f6-754d74333aa59564

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): no

OEIS matches ?

No OEIS matches.

OEIS submission text ?

Fields to paste into an OEIS submission: the example %e, the formula %F and programs %t (Mathematica) and %o (PARI/GP) that list the same rows. For an OEIS link the row numbers, the offset and the orientation are those of the entry, as matched; the matched terms were compared with the published ones, which identifies the node with the entry on a finite prefix, not for every n. The PARI/GP program is not machine-checked here.

The atlas's own rows: n = 0, …, ascending powers of x

%e Example

Triangle begins:
  0:    1;
  1:    3,     2;
  2:    8,    12,      3;
  3:   21,    50,     27,      4;
  4:   55,   180,    153,     48,      5;
  5:  144,   600,    702,    344,     75,     6;
  6:  377,  1908,   2853,   1920,    650,   108,     7;
  7:  987,  5878,  10719,   9220,   4275,  1098,   147,    8;
  8: 2584, 17700,  38121,  40032,  23700,  8316,  1715,  192,   9;
  9: 6765, 52390, 130194, 161704, 116865, 52290, 14700, 2528, 243, 10;

%F Formula

The row polynomials satisfy -(20*n+6*n*x-2*n^3*x^2)*P(n,x) = -(30*n+30+(5*n^2+29*n+24)*x-(3*n^3+3*n^2-6*n-6)*x^2-(n^3+2*n^2+n)*x^3)*P(n-1,x) - (25+45*x-(5*n^2+5*n-23)*x^2-(6*n^2+6*n-3)*x^3-(n^2+n)*x^4)*d/dx P(n-1,x) for n >= 1, with P(0,x) = 1.

%t Mathematica

P[0, x_] := 1;
P[n_, x_] := P[n, x] = Expand[Together[(-(30*n + 30 + (5*n^2 + 29*n + 24)*x - (3*n^3 + 3*n^2 - 6*n - 6)*x^2 - (n^3 + 2*n^2 + n)*x^3)*P[n - 1, x] - (25 + 45*x - (5*n^2 + 5*n - 23)*x^2 - (6*n^2 + 6*n - 3)*x^3 - (n^2 + n)*x^4)*D[P[n - 1, x], x])/(-20*n - 6*n*x + 2*n^3*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; for(n = 1, N, my(i = n + 1); v[i] = (-(30*n + 30 + (5*n^2 + 29*n + 24)*x - (3*n^3 + 3*n^2 - 6*n - 6)*x^2 - (n^3 + 2*n^2 + n)*x^3)*v[i - 1] - (25 + 45*x - (5*n^2 + 5*n - 23)*x^2 - (6*n^2 + 6*n - 3)*x^3 - (n^2 + n)*x^4)*deriv(v[i - 1], x))/(-20*n - 6*n*x + 2*n^3*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)

Generated with polytool c48629374597.

Proved properties

Real-rooted. Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, 0]
Every polynomial of the sequence has only real roots, inside the stated interval.

by the cited steps: e-997ef18dd206f0e8
Coefficients of one sign. Every nonzero row, n >= 0: the coefficients of P_n have one sign
All coefficients of each polynomial have the same sign (after x -> -x when alternating).

derived from the cited steps by a stated theorem: e-997ef18dd206f0e8
Hadamard kernel (Malo). Rows P_n, n >= 0, are Hadamard kernels (preserve real-rootedness)
Multiplying the coefficients of any real-rooted polynomial termwise by those of a row (Hadamard product) gives a real-rooted polynomial again.

derived from the cited steps by a stated theorem: e-997ef18dd206f0e8
Interlacing of consecutive rows. Rows P_(m-1), P_m interlace (weak, unordered) for every m >= 1
The roots of consecutive polynomials alternate on the real line.

by the cited steps: e-997ef18dd206f0e8

Proof chains

1 incoming proof step. Each step is expanded back to the roots of the proof DAG, the theorem checks of a node's own rule. JSON

preserver_image euler_polynomial, shift 0 e-997ef18dd206f0e8

Laguerre’s theorem on multiplier sequences [SP14; Bra15, Thm 40] polytool ?
- premise (sequence): A convolution triangle of numbers based on A001906 (even-indexed Fibonacci numbers).
  uses: Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, 0]
  - theorem_check three_term_recurrence e-af8f298ca8f41adf root: theorem check
    
    Three-term recurrence criterion [Sze39, §3.3; Fav35] polytool ?
  - theorem_check three_term_recurrence e-c7df247a48c8552e root: theorem check
    
    Three-term recurrence criterion [Sze39, §3.3; Fav35] polytool ?

Related sequences ?

No candidate equalities or related sequences.

References

[Bra15] Petter Brändén. Unimodality, log-concavity, real-rootedness and beyond. Handbook of enumerative combinatorics, :437–483, March 2015. doi:10.1201/b18255-10
[Fav35] Jean Favard. Sur les polynômes de tchebicheff. C. R. Acad. Sci. Paris, 200:2052–2053, 1935.
[SP14] J Schur and G Polya. Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen. J. Reine Angew. Math., 1914.
[Sze39] G. Szegő. Orthogonal Polynomials. Colloquium publications, American Mathematical Society, 1939. doi:10.1090/coll/023