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A073578 Sum(k=1,n,mu(2*k)). 0
-1, -1, 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 4, 4, 3, 3, 4, 4, 5, 5, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 7, 7, 6, 6, 5, 5, 6, 6, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 7, 7, 8, 8, 7, 7, 6, 6, 7, 7, 8, 8, 8, 8, 7, 7, 8, 8, 7, 7, 8, 8, 9, 9, 9, 9, 8, 8, 9, 9, 9, 9, 10, 10, 9, 9, 8, 8, 9, 9, 8, 8, 7, 7, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

After a(2)=-1, the next negative value is a(8511)=-1.

Observation: It seems that sum(k=1,n,a(k)) is usually close to n*log(n)*log(log(n)). Is sum(k=1,n,a(k)) asymptotic to C*n*log(n)*log(log(n)) for some C near 1?

LINKS

Table of n, a(n) for n=1..104.

MATHEMATICA

Accumulate[MoebiusMu[2Range[110]]] (* Harvey P. Dale, Apr 30 2012 *)

CROSSREFS

Sequence in context: A064658 A194292 A308403 * A087866 A061392 A048273

Adjacent sequences:  A073575 A073576 A073577 * A073579 A073580 A073581

KEYWORD

easy,sign

AUTHOR

Benoit Cloitre, Aug 28 2002

EXTENSIONS

Edited by Dean Hickerson, Sep 04 2002

STATUS

approved

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Last modified March 28 14:24 EDT 2020. Contains 333089 sequences. (Running on oeis4.)