A219098 Parity of primepi(3^n).

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

Offset

0

Comments

The parity of pi(n) is obtained without calculating pi(n), and much more quickly. See the paper below.

Links

Table of n, a(n) for n=0..56.

Henri Lifchitz, Parity of pi(n)

Example

For n = 4, primepi(3^4) = 22 = 0 (mod 2).

Mathematica

Table[Mod[PrimePi[3^n], 2], {n, 0, 25}] (* T. D. Noe, Nov 12 2012 *)

Crossrefs

Cf. A006880, A055729, A219071, A219097.

Sequence in context: A135136 A137331 A093386 * A288710 A179827 A285133

Adjacent sequences: A219095 A219096 A219097 * A219099 A219100 A219101

Keyword

nonn

Author

Henri Lifchitz, Nov 11 2012

Status

approved