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A070077 Greatest common divisor of n-th squarefree number and n-th cubefree number. 1
1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 2, 1, 2, 1, 3, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is squarefree;

Conjecture: for any squarefree k exists m such that a(m)=k; see A070078.

LINKS

Table of n, a(n) for n=1..90.

Eric Weisstein's World of Mathematics, Squarefree.

Eric Weisstein's World of Mathematics, Cubefree.

FORMULA

a(n) = GCD(A005117(n), A004709(n)).

EXAMPLE

a(10) = GCD(A005117(10), A004709(10)) = GCD(14,11) = 1.

a(11) = GCD(A005117(11), A004709(11)) = GCD(15,12) = 3*GCD(5,4) = 3*1 = 3.

CROSSREFS

Sequence in context: A321895 A321899 A027870 * A337200 A337201 A327462

Adjacent sequences:  A070074 A070075 A070076 * A070078 A070079 A070080

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Apr 22 2002

STATUS

approved

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Last modified January 16 18:07 EST 2022. Contains 350376 sequences. (Running on oeis4.)