A305564 Number of finite sets of relatively prime positive integers with least common multiple n.

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

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 * A354873 A345301 A160417

Adjacent sequences: A305561 A305562 A305563 * A305565 A305566 A305567

Keyword

nonn

Author

Gus Wiseman, Jun 05 2018

Status

approved