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 A219097 Parity of pi(2^n). 4
 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 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 Henri Lifchitz, Parity of pi(n) EXAMPLE For n = 5 , pi(2^5) = 11 = 1 (mod 2). MAPLE A071986 := proc(n)     numtheory[pi](n) mod 2 ; end proc: A219097 := proc(n)     A071986(2^n) ; end proc: # R. J. Mathar, Nov 12 2012 MATHEMATICA Table[Mod[PrimePi[2^n], 2], {n, 32}] (* Alonso del Arte, Nov 12 2012 *) CROSSREFS Cf. A071986, A131378, A006880, A219071. Sequence in context: A285969 A189664 A260446 * A284751 A288426 A286052 Adjacent sequences:  A219094 A219095 A219096 * A219098 A219099 A219100 KEYWORD nonn AUTHOR Henri Lifchitz, Nov 11 2012 STATUS approved

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Last modified November 19 14:52 EST 2018. Contains 317352 sequences. (Running on oeis4.)