login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A219098 Parity of primepi(3^n). 2
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 (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..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: A234577 A252742 A252743 * A274950 A191153 A214210

Adjacent sequences:  A219095 A219096 A219097 * A219099 A219100 A219101

KEYWORD

nonn

AUTHOR

Henri Lifchitz, Nov 11 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified March 28 22:27 EDT 2017. Contains 284249 sequences.