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A160115 Fluctuations of the number of cubefree integers not exceeding 2^n +0
2
0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 2, 2, 3, 0, -1, -1, 1, 2, 0, -1, 0, 2, 6, 1, 2, 7, 5, -1, -7, -4, 4, -7, -21, -7, -2, 30, 2, 14, -8, 7, -1, -7, -12, -1, 21, 28, 7, -29, -33, -76, -88, 15, 47, 58, -51, -112, 293, 122, 316, -96, -42, -259, 140, -111, 6, -790, -342, 146, 395, 1087 (list; graph; listen)
OFFSET

0,11

COMMENT

The asymptotic density of cubefree integers is the reciprocal of Apery's constant 1/zeta(3) = 0.83190737258... The number of cubefree integers not exceeding N is thus roughly N/zeta(3). When N is a power of 2, this sequence gives the difference between the actual number (A160113) and that linear estimate (rounded to the nearest integer).

LINKS

G. P. Michon, Reciprocal of Apery's constant.

G. P. Michon, On the number of cubefree integers not exceeding N.

Eric Weisstein's World of Mathematics, Cubefree.

FORMULA

a(n) = A160113(n)-round(2^n/zeta(3))

CROSSREFS

A004709 (cube-free integers). A160112 & A160113 (counting cubefree integers).

Sequence in context: A057330 A079243 A073438 this_sequence A139365 A071479 A091426

Adjacent sequences: A160112 A160113 A160114 this_sequence A160116 A160117 A160118

KEYWORD

easy,sign

AUTHOR

Gerard P. Michon (g.michon(AT)att.net), May 06 2009

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Last modified November 24 14:25 EST 2009. Contains 167438 sequences.


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