A099097 → basis A013609

nonnegative coefficients

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

Recurrence
\(P_{n}(x) = \left(1 + 2\,x\right)\,P_{n-2}(x) + \left(3 + 6\,x\right)\,P_{n-1}(x)\)
\(P_{1}(x) = 1\)
\(P_{2}(x) = 3 + 6\,x\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14Pn(1)
111
2369
310383684
433186348216783
51098142272280812967299
63603348124202296821168777668040
71189132366124815077620822415292846656634257
83927509102822768676241596432175824010730882799365912433
912970191906124000845698001050481615422688141212167371648167961655114668
1042837712302525555622581624622649281142480641394893441092683524982860810077696513769311
1114148126117742166430010632802434192894475276608011489230081200355200821518848332563968604661764789267803
124672809482184873437044820626081771183152454864982483313509761088285068899350530566036539904219693772836279705644644718160
1315433213414496834581206421199066728760510096257096723525494040704086134859136983244925447969553971243535646720143909498882176782336416170266849
145097243122111574134861407290913424164173627868813778309376033650790585661559257228884348338688085494022041662305019596830914340249693601640448130606940163879466556121
151683505043414979051926136603817724248019275721400070699764595219425820318724061840825216649459980518479020655073287201718636544476719362662421666240184326051454894087836416409636163709805636

Computed in your browser ?

Technical details
Node id
n-6321b10e19f62245 · revision 1 · JSON
Definition source
derived:basis_map_A013609
Fingerprint
f6-f2c232606f089033

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 -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): 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 = 1, …, ascending powers of x
%e Example
Triangle begins:
   1:     1;
   2:     3,      6;
   3:    10,     38,      36;
   4:    33,    186,     348,      216;
   5:   109,    814,    2272,     2808,     1296;
   6:   360,   3348,   12420,    22968,    21168,      7776;
   7:  1189,  13236,   61248,   150776,   208224,    152928,     46656;
   8:  3927,  50910,  282276,   867624,  1596432,   1758240,   1073088,    279936;
   9: 12970, 191906, 1240008,  4569800, 10504816,  15422688,  14121216,   7371648,  1679616;
  10: 42837, 712302, 5255556, 22581624, 62264928, 114248064, 139489344, 109268352, 49828608, 10077696;
%F Formula
The row polynomials satisfy P(n,x) = (1+2*x)*P(n-2,x) + (3+6*x)*P(n-1,x) for n >= 3, with P(1,x) = 1, P(2,x) = 3 + 6*x.
%t Mathematica
P[1, x_] := 1;
P[2, x_] := 3 + 6*x;
P[n_, x_] := P[n, x] = Expand[(1 + 2*x)*P[n - 2, x] + (3 + 6*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] = 1; v[2] = 3 + 6*x; for(n = 3, N, my(i = n); v[i] = (1 + 2*x)*v[i - 2] + (3 + 6*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)

Generated with polytool c48629374597.

Proved properties

  • Real-rooted. Every row P_n, n >= 1, 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-9d236d9db88b150c
  • Coefficients of one sign. Every nonzero row, n >= 1: 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-9d236d9db88b150c
  • Hadamard kernel (Malo). Rows P_n, n >= 1, 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-9d236d9db88b150c

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

No candidate equalities or related sequences.

References

  1. [MW08] Shi-Mei Ma and Yi Wang. q-Eulerian polynomials and polynomials with only real zeros. The Electronic Journal of Combinatorics, 15(1):Research Paper 17, January 2008. doi:10.37236/741