A219189 Parity of pi(5^n).

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

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..38.

Henri Lifchitz, Parity of pi(n)

Example

a(4) = pi(5^4) mod 2 = 114 mod 2 = 0.

Mathematica

Table[Mod[PrimePi[5^n], 2], {n, 10}]

Crossrefs

Cf. A006880, A219071, A219097, A219098.

Sequence in context: A189011 A189135 A369961 * A029691 A209229 A365089

Adjacent sequences: A219186 A219187 A219188 * A219190 A219191 A219192

Keyword

nonn

Author

Henri Lifchitz, Nov 14 2012

Status

approved