basis-map coefficients of A127647 → basis A007318

nonnegative coefficientsonly rational roots

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

Recurrence

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

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14Pn(1)
011
1213
288218
3243618381
480160120405405
52566406403208081944
6832249631202080780156139477
7268894081411211760588017642942145927
887043481660928609283808015232380854434223074
928160126720253440295680221760110880369607920990551082565
109113645568010252801367040119616071769629904085440160201780895255361
1129491216220164055040608256060825604257792212889676032019008031680316814425509168
129543685726208157470722624512029525760236206081377868859051521845360410080615125592233123825753
133088384200744966022348811040972813801216012421094482807296414036481552636843128808625761176249802377601059771
149994240699596802273689604547379206252646406252646404689484802679705601172371203907904097697601776320222040170806102917611090
Technical details
Node id
n-bfcfc0c48e00f4c8 · revision 0 · JSON
Definition source
derived:shift_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:     2,      1;
  2:     8,      8,      2;
  3:    24,     36,     18,      3;
  4:    80,    160,    120,     40,      5;
  5:   256,    640,    640,    320,     80,      8;
  6:   832,   2496,   3120,   2080,    780,    156,    13;
  7:  2688,   9408,  14112,  11760,   5880,   1764,   294,   21;
  8:  8704,  34816,  60928,  60928,  38080,  15232,  3808,  544,  34;
  9: 28160, 126720, 253440, 295680, 221760, 110880, 36960, 7920, 990, 55;
%F Formula
The row polynomials satisfy P(n,x) = (4+4*x+x^2)*P(n-2,x) + (2+x)*P(n-1,x) for n >= 2, with P(0,x) = 1, P(1,x) = 2 + x.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 2 + x;
P[n_, x_] := P[n, x] = Expand[(4 + 4*x + x^2)*P[n - 2, x] + (2 + 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] = 1; v[2] = 2 + x; for(n = 2, N, my(i = n + 1); v[i] = (4 + 4*x + x^2)*v[i - 2] + (2 + 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)

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.