A010848 - OEIS

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A010848

Number of numbers k <= n such that at least one prime factor of n is not a prime factor of k.

6

0, 1, 2, 2, 4, 5, 6, 4, 6, 9, 10, 10, 12, 13, 14, 8, 16, 15, 18, 18, 20, 21, 22, 20, 20, 25, 18, 26, 28, 29, 30, 16, 32, 33, 34, 30, 36, 37, 38, 36, 40, 41, 42, 42, 42, 45, 46, 40, 42, 45, 50, 50, 52, 45, 54, 52, 56, 57, 58, 58, 60, 61, 60, 32, 64, 65, 66, 66, 68, 69, 70, 60

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OFFSET

1,3

LINKS

Robert Israel,Table of n, a(n) for n = 1..10000

FORMULA

a(n) = n-A003557(n). -Vladeta Jovovic,Sep 15 2006

MAPLE

f:= n -> n - n/convert(numtheory:-factorset(n), `*`):

map(f, [$1..100]); #Robert Israel,Apr 10 2018

CROSSREFS

Cf.A008479,A010846,A010847.

Sequence in context:A364049 A368866 A137413*A133937 A181523 A353855

Adjacent sequences:A010845 A010846 A010847*A010849 A010850 A010851

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

EXTENSIONS

Definition corrected byVladeta Jovovic,Sep 15 2006

STATUS

approved