basis-map coefficients of A127647 → basis A013609

palindromicγ-positivenonnegative coefficientsonly rational roots

Proved for all n all roots real, in (−∞, 0]coefficients of one signHadamard kernel

Recurrence

\(P_{n}(x) = \left(4 + 8\,x + 4\,x^{2}\right)\,P_{n-2}(x) + \left(2 + 2\,x\right)\,P_{n-1}(x)\)
\(P_{0}(x) = 1\)
\(P_{1}(x) = 2 + 2\,x\)

Rows ?

nx0x1x2x3x4x5x6x7x8x9x10x11x12x13x14Pn(1)
011
1224
2816832
324727224192
480320480320801280
525612802560256012802568192
68324992124801664012480499283253248
726881881656448940809408056448188162688344064
88704696322437124874246092804874242437126963287042228224
9281602534401013760236544035481603548160236544010137602534402816014417920
10911369113604101120109363201913856022966272191385601093632041011209113609113693323264
1129491232440321622016048660480973209601362493441362493449732096048660480162201603244032294912603979776
12954368114524166298828820996096047241216075585945688183603275585945647241216020996096062988288114524169543683909091328
1330883844014899224089395288327782422081945603974750208529966694452996669443974750208220819456088327782424089395240148992308838425300041728
14999424013991936090947584036379033601000423424020008468480300127027203430023168030012702720200084684801000423424036379033609094758401399193609994240163745628160
Technical details
Node id
n-a9d69759f5d3bd95 · revision 0 · JSON
Definition source
derived:basis_map_A013609
Fingerprint
f6-77a7ed3b1d5f257e

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: yes
  • γ-positive (gamma_positive): yes
  • 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,      2;
  2:     8,     16,       8;
  3:    24,     72,      72,      24;
  4:    80,    320,     480,     320,      80;
  5:   256,   1280,    2560,    2560,    1280,     256;
  6:   832,   4992,   12480,   16640,   12480,    4992,     832;
  7:  2688,  18816,   56448,   94080,   94080,   56448,   18816,    2688;
  8:  8704,  69632,  243712,  487424,  609280,  487424,  243712,   69632,   8704;
  9: 28160, 253440, 1013760, 2365440, 3548160, 3548160, 2365440, 1013760, 253440, 28160;
%F Formula
The row polynomials satisfy P(n,x) = (4+8*x+4*x^2)*P(n-2,x) + (2+2*x)*P(n-1,x) for n >= 2, with P(0,x) = 1, P(1,x) = 2 + 2*x.
%t Mathematica
P[0, x_] := 1;
P[1, x_] := 2 + 2*x;
P[n_, x_] := P[n, x] = Expand[(4 + 8*x + 4*x^2)*P[n - 2, x] + (2 + 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 + 2*x; for(n = 2, N, my(i = n + 1); v[i] = (4 + 8*x + 4*x^2)*v[i - 2] + (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.