OFFSET
1,2
COMMENTS
Two or more numbers are pairwise coprime if no pair of them has a common divisor > 1.
FORMULA
a(n) = A276187(n) + 1. - Gus Wiseman, May 08 2021
EXAMPLE
The a(4) = 8 subsets of {1,2,3,4} are {1}, {1,2}, {1,3}, {1,4}, {2,3}, {3,4}, {1,2,3}, {1,3,4}. - Michael B. Porter, Jan 12 2019
From Gus Wiseman, May 09 2021: (Start)
The a(2) = 2 through a(6) = 22 sets:
{1} {1} {1} {1} {1}
{1,2} {1,2} {1,2} {1,2} {1,2}
{1,3} {1,3} {1,3} {1,3}
{2,3} {1,4} {1,4} {1,4}
{1,2,3} {2,3} {1,5} {1,5}
{3,4} {2,3} {1,6}
{1,2,3} {2,5} {2,3}
{1,3,4} {3,4} {2,5}
{3,5} {3,4}
{4,5} {3,5}
{1,2,3} {4,5}
{1,2,5} {5,6}
{1,3,4} {1,2,3}
{1,3,5} {1,2,5}
{1,4,5} {1,3,4}
{2,3,5} {1,3,5}
{3,4,5} {1,4,5}
{1,2,3,5} {1,5,6}
{1,3,4,5} {2,3,5}
{3,4,5}
{1,2,3,5}
{1,3,4,5}
(End)
MATHEMATICA
Table[Length[Select[Subsets[Range[n]], CoprimeQ@@#&]], {n, 10}]
CROSSREFS
The case of pairs is A015614.
The case with singletons is A187106.
The version without singletons (except {1}) is A276187.
Row sums of A320436.
The version for divisors > 1 is A343654.
The version for divisors without singletons is A343655.
The maximal version is A343659.
A018892 counts coprime unordered pairs of divisors.
A051026 counts pairwise indivisible subsets of {1...n}.
A087087 ranks pairwise coprime subsets of {1...n}.
A326675 ranks pairwise coprime non-singleton subsets of {1...n}.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 08 2019
EXTENSIONS
a(25)-a(43) from Alois P. Heinz, Jan 08 2019
STATUS
approved