A072629 Parity of n*floor(log n).

0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,1

Comments

a(n)=1 for n: 3, 5, 7, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 149, 151, .... - Robert G. Wilson v, Feb 01 2015

Links

Antti Karttunen, Table of n, a(n) for n = 1..100000

Index entries for characteristic functions

Formula

a(n) = n*floor(log(n)) mod 2.

Example

Parity either alternates or it is steadily 0. Intervals of such kind also change and return: 01010...0000....0101.., etc.

Mathematica

f[n_] := Mod[n*Floor@ Log@ n, 2]; Array[f, 105] (* Robert G. Wilson v, Feb 01 2015 *)

Prog

(PARI) a(n) = (log(n)\1*n)%2; \\ Charles R Greathouse IV, Sep 04 2015, corrected by Antti Karttunen, Feb 06 2019

Crossrefs

Cf. A004648, A072608, A072609, A072610, A072630.

Sequence in context: A060510 A327205 A219071 * A164292 A337802 A257531

Adjacent sequences: A072626 A072627 A072628 * A072630 A072631 A072632

Keyword

nonn

Author

Labos Elemer, Jun 28 2002

Status

approved