

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



