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A065357 (-1)^pi(n) where pi(n) is the number of primes <= n. 3
1, 1, -1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, 1, 1 (list; graph; refs; listen; history; internal format)
OFFSET

0,1

LINKS

Harry J. Smith, Table of n, a(n) for n=0,...,1000

PROG

(PARI) { for (n=0, 1000, if (n, a=(-1)^primepi(n), a=1); write("b065357.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 30 2009]

CROSSREFS

Cf. A000720.

Sequence in context: A143431 A064179 * A121241 A122188 A000012 A158388

Adjacent sequences:  A065354 A065355 A065356 * A065358 A065359 A065360

KEYWORD

easy,sign

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Oct 31 2001

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Last modified February 17 12:38 EST 2012. Contains 206021 sequences.