[go: up one dir, main page]

login
A175739
Triangle T(n,m) with the coefficient [x^m] of the polynomial x^(2*n) - x^(2*n - 1) - x^n - x + 1 in row n, column m, 1 <= m <= 2*n. T(0,0) = 1.
5
1, 1, -3, 1, 1, -1, -1, -1, 1, 1, -1, 0, -1, 0, -1, 1, 1, -1, 0, 0, -1, 0, 0, -1, 1, 1, -1, 0, 0, 0, -1, 0, 0, 0, -1, 1, 1, -1, 0, 0, 0, 0, -1, 0, 0, 0, 0, -1, 1, 1, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 1, 1, -1, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, -1, 1, 1, -1, 0, 0, 0, 0, 0, 0, 0
OFFSET
0,3
COMMENTS
The polynomials up to n = 10 are Salem polynomials (the third lowest Salem in the table).
LINKS
Michael Mossinghoff, Small Salem Numbers
William J. Floyd, Growth of planar Coxeter groups, P.V. numbers, and Salem numbers, Math. Ann. Vol. 293 (1992), 475-483.
FORMULA
Sum_{m=0..2*n} T(n,m)= -1.
From Franck Maminirina Ramaharo, Nov 02 2018: (Start)
G.f.: (1 - 4*x*y + x*(2 + x + 2*x^2)*y^2 - x^2*(1 + x^2)*y^3)/((1 - y)*(1 - x*y)*(1 - x^2*y)).
E.g.f.: (-(1 - x)*exp(x^2*y) - x*exp(x*y) + x*(1 - x)*exp(y) + 1 + x^2)/x. (End)
EXAMPLE
The polynomial coefficients are
1;
1, -3, 1;
1, -1, -1, -1, 1;
1, -1, 0, -1, 0, -1, 1;
1, -1, 0, 0, -1, 0, 0, -1, 1;
1, -1, 0, 0, 0, -1, 0, 0, 0, -1, 1;
1, -1, 0, 0, 0, 0, -1, 0, 0, 0, 0, -1, 1;
1, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 1;
1, -1, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, -1, 1;
1, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, -1, 1;
1, -1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1;
...
The corresponding Mahler measures are
-----------------------------------------------------
n | M(p_n) || n | M(p_n)
-----------------------------------------------------
1 | 1.7220838057390422450 || 6 | 1.2612309611
2 | 1.5061356795538388 || 7 | 1.2363179318
3 | 1.40126836793 || 8 | 1.21639166113826509
4 | 1.337313210201 || 9 | 1.200026523
5 | 1.293485953125 || 10 | 1.286735
...
MATHEMATICA
p[x_, n_] = If[n == 0, 1, x^(2*n) - x^(2*n - 1) - x^n - x + 1];
Table[CoefficientList[p[x, n], x], {n, 0, 10}]//Flatten
PROG
(Maxima) T(n, k) := if n = 0 and k = 0 then 1 else ratcoef(x^(2*n) - x^(2*n - 1) - x^n - x + 1, x, k)$
create_list(T(n, k), n, 0, 10, k, 0, 2*n); /* Franck Maminirina Ramaharo, Nov 02 2018 */
CROSSREFS
Cf. A143439.
Sequence in context: A176851 A205535 A172972 * A371149 A260196 A358692
KEYWORD
sign,easy,tabf
AUTHOR
Roger L. Bagula, Dec 04 2010
STATUS
approved