This site is supported by donations to The OEIS Foundation.

The OEIS is looking to hire part-time people to help edit core sequences, upload scanned documents, process citations, fix broken links, etc. - Neil Sloane, njasloane@gmail.com

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

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.