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 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 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 * A285133 A274950 A191153 Adjacent sequences:  A219095 A219096 A219097 * A219099 A219100 A219101 KEYWORD nonn AUTHOR Henri Lifchitz, Nov 11 2012 STATUS approved

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