A013611 → Pₙ + Pₙ₊₁

nonnegative coefficients only rational roots

Proved for all n: all roots real what this means

Recurrence
\(P_{n}(x) = \left(1 + 4\,x\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 2 + 4\,x\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14x15Pn(1)
0246
12121630
22206464150
3228144320256750
4236256896153610243750
5244400192051207168409618750
625257635201280027648327681638493750
72607845824268807884814336014745665536468750
826810248960501761863684587527208966553602621442343750
9276129613056860163870721204224255590435389442883584104857611718750
1028416001824013824073113627525127372800137625601703936012582912419430458593750
1129219362464021120012840965677056183828484325376072089600807403525452595216777216292968750
12210023043238430976021288961081344041091072116785152245104640369098752377487360234881024671088641464843750
1321082704416004392963367936193290248434483228114944071224524813495173121853882368174483046410066329602684354567324218750
142116313652416605696512512032800768161660928618528768183684300841984983047251951616916035993679859548164294967296107374182436621093750

Computed in your browser ?

Technical details
Node id
n-e9fc958a2cab6bd7 · revision 1 · JSON
Definition source
derived:obreschkoff_combination
Fingerprint
f6-13cd5a379fa767ee

Observed on the stored rows ?

  • Degrees: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 (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

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: 2,  4;
  1: 2, 12,   16;
  2: 2, 20,   64,    64;
  3: 2, 28,  144,   320,   256;
  4: 2, 36,  256,   896,  1536,   1024;
  5: 2, 44,  400,  1920,  5120,   7168,    4096;
  6: 2, 52,  576,  3520, 12800,  27648,   32768,   16384;
  7: 2, 60,  784,  5824, 26880,  78848,  143360,  147456,   65536;
  8: 2, 68, 1024,  8960, 50176, 186368,  458752,  720896,  655360,  262144;
  9: 2, 76, 1296, 13056, 86016, 387072, 1204224, 2555904, 3538944, 2883584, 1048576;
%F Formula
The row polynomials satisfy P(n,x) = (1+4*x)*P(n-1,x) for n >= 1, with P(0,x) = 2 + 4*x.
%t Mathematica
P[0, x_] := 2 + 4*x;
P[n_, x_] := P[n, x] = Expand[(1 + 4*x)*P[n - 1, x]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten
%o PARI/GP
P(N) = {my(v = vector(N + 1)); v[1] = 2 + 4*x; for(n = 1, N, my(i = n + 1); v[i] = (1 + 4*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 - 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, +inf)
    Every polynomial of the sequence has only real roots, inside the stated interval.
    by the cited steps: e-1866a96f98a4765c

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. [ASW52] Michael Aissen, I. J. Schoenberg and A. M. Whitney. On the generating functions of totally positive sequences I. Journal d’Analyse Mathématique, 2(1):93–103, 1952. doi:10.1007/BF02786970
  2. [AW24] Christos A. Athanasiadis and David G. Wagner. Veronese sections and interlacing matrices of polynomials and formal power series. arXiv:2404.12989. arXiv
  3. [Edr53] Albert Edrei. Proof of a Conjecture of Schoenberg on the Generating Function of a Totally Positive Sequence. Canadian Journal of Mathematics, 5:86–94, 1953. doi:10.4153/CJM-1953-010-3
  4. [Fis06] Steve Fisk. Polynomials, roots, and interlacing. arXiv:math/0612833. arXiv
  5. [LW07] Lily L. Liu and Yi Wang. A unified approach to polynomial sequences with only real zeros. Advances in Applied Mathematics, 38(4):542–560, May 2007. doi:10.1016/j.aam.2006.02.003
  6. [Obr63] Nikola Obreschkoff. Verteilung und berechnung der nullstellen reeller polynome. Hochschulbücher für mathematik, VEB Deutscher Verlag der Wissenschaften, 1963.