A257593 Number of zeros of the polynomial Sum_{j=0..n-1} z^(2^j-1)outside the unit circle.

2, 4, 10, 18, 46, 100, 204, 420, 840, 1708, 3478, 7066, 14286, 28772

Offset

3,1

Links

Table of n, a(n) for n=3..16.

Karl Dilcher and Larry Ericksen, The Polynomials of Mahler and Roots of Unity, The American Mathematical Monthly, Vol. 122, No. 04 (April 2015), pp. 338-353.

Mathematica

 Table[Length[Select[Flatten[Abs[z/.NSolve[Sum[z^(2^j-1), {j, 0, n-1}]==0]]], #>1&]], {n, 3, 13}] (* Vincenzo Librandi, Sep 30 2017 *)

Crossrefs

Cf. A257592.

Sequence in context: A104723 A206140 A079162 * A197926 A228705 A253772

Adjacent sequences: A257590 A257591 A257592 * A257594 A257595 A257596

Keyword

nonn,more

Author

N. J. A. Sloane, May 15 2015

Status

approved