Real-rooted atlas

basis-map coefficients of A026729 → basis A013610 → basis A008288

nonnegative coefficients

Proved for all n all roots real, in [−3−2√2, −3+2√2]coefficients of one signHadamard kernel

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14Pn(1)
111
2437
31633958
46422516227478
525612811647675813940
610246657127809180259224332476
74096327698496991422442269477729267688
8163841556495119747519775401081946433353421872206456
9655367208972883555543993353280992820987805545115911656118187024
1026214432768011546646435914266453117243255130813524408318864639366019683149909104
111048576146800657995388522151232034562862031937635817897970660886080122034601318761590491235646880
12419430465011713401604570129656497524269187602775432762199423782090976138226123277645487413436962617714710184993248
13167772162852126731971322839728131261515970848165219541863781949782671011361854286435195066610790811091659867391434890753144183951239744
146710886412415139859495904212395438991129976989348016114325789717202733797612362913295260258953376198367045474322622996595213920467668081594323691979904448
152684354565368709121450300476972089098947705972856477661113034313403139730027499912057672218047229454887883017557624238693376831916882463394210344347815146068547829695703741715072
Technical details
Node id
n-1ab5ed4ed816e2da · revision 0 · JSON
Definition source
derived:basis_map_A008288
Fingerprint
f6-52999a0df2a941cc

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

Matches ?

No OEIS matches.

Submission text ?

Atlas rows n = 1, …, ascending powers of x
%e Example
Triangle begins:
   1:      1;
   2:      4,       3;
   3:     16,      33,        9;
   4:     64,     225,      162,       27;
   5:    256,    1281,     1647,      675,       81;
   6:   1024,    6657,    12780,     9180,     2592,      243;
   7:   4096,   32769,    84969,    91422,    44226,     9477,      729;
   8:  16384,  155649,   511974,   751977,   540108,   194643,    33534,    2187;
   9:  65536,  720897,  2883555,  5439933,  5328099,  2820987,   805545,  115911,   6561;
  10: 262144, 3276801, 15466464, 35914266, 45311724, 32551308, 13524408, 3188646, 393660, 19683;
%F Formula
The row polynomials satisfy P(n,x) = -(4-6*x)*P(n-2,x) + (5+3*x)*P(n-1,x) for n >= 3, with P(1,x) = 1, P(2,x) = 4 + 3*x.
%t Mathematica
P[1, x_] := 1;
P[2, x_] := 4 + 3*x;
P[n_, x_] := P[n, x] = Expand[-(4 - 6*x)*P[n - 2, x] + (5 + 3*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] = 4 + 3*x; for(n = 3, N, my(i = n); v[i] = -(4 - 6*x)*v[i - 2] + (5 + 3*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

  • Real-rooted? Every row P_n, n ≥ 1, is zero or real-rooted with all roots in [−3−2√2, −3+2√2] (rational outer bound [-1564556493/268435456, -46056243/268435456])
    by Affine-current basis map theorem
  • Coefficients of one sign? Every nonzero row, n ≥ 1: the coefficients of P_n have one sign
    derived from Affine-current basis map theorem
  • Hadamard kernel (Malo)? Rows P_n, n ≥ 1, are Hadamard kernels (preserve real-rootedness)
    derived from Affine-current basis map theorem

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.