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A219189 Parity of pi(5^n). 0
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 (list; graph; refs; listen; history; text; internal format)
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: A188076 A189011 A189135 * A209229 A284622 A215581

Adjacent sequences:  A219186 A219187 A219188 * A219190 A219191 A219192

KEYWORD

nonn

AUTHOR

Henri Lifchitz, Nov 14 2012

STATUS

approved

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Last modified July 24 16:24 EDT 2017. Contains 289775 sequences.