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A305564 Number of finite sets of relatively prime positive integers with least common multiple n. 4
1, 1, 1, 2, 1, 7, 1, 4, 2, 7, 1, 32, 1, 7, 7, 8, 1, 32, 1, 32, 7, 7, 1, 136, 2, 7, 4, 32, 1, 193, 1, 16, 7, 7, 7, 322, 1, 7, 7, 136, 1, 193, 1, 32, 32, 7, 1, 560, 2, 32, 7, 32, 1, 136, 7, 136, 7, 7, 1, 3464, 1, 7, 32, 32, 7, 193, 1, 32, 7, 193, 1, 2852, 1, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..74.

EXAMPLE

The a(6) = 7 sets are {1,6}, {2,3}, {1,2,3}, {1,2,6}, {1,3,6}, {2,3,6}, {1,2,3,6}.

MATHEMATICA

Table[Length[Select[Rest[Subsets[Divisors[n]]], And[GCD@@#==1, LCM@@#==n]&]], {n, 100}]

CROSSREFS

Cf. A001055, A071625, A076078, A181819, A275870, A281116, A285573, A285572, A290103, A304818, A305563, A305565, A305566, A305567.

Sequence in context: A178618 A155992 A178211 * A160417 A117044 A280691

Adjacent sequences:  A305561 A305562 A305563 * A305565 A305566 A305567

KEYWORD

nonn

AUTHOR

Gus Wiseman, Jun 05 2018

STATUS

approved

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Last modified August 10 02:02 EDT 2020. Contains 336365 sequences. (Running on oeis4.)