OFFSET
0,3
COMMENTS
The pairs are not required to be strict.
LINKS
Fausto A. C. Cariboni, Table of n, a(n) for n = 0..90
FORMULA
For n > 0, a(n) = A326490(n) - 1.
EXAMPLE
The a(1) = 1 through a(6) = 17 subsets:
{} {} {} {} {} {}
{2} {2} {2} {2} {2}
{3} {3} {3} {3}
{2,3} {4} {4} {4}
{2,3} {5} {5}
{3,4} {2,3} {6}
{2,5} {2,3}
{3,4} {2,5}
{3,5} {2,6}
{4,5} {3,4}
{3,4,5} {3,5}
{4,5}
{4,6}
{5,6}
{2,5,6}
{3,4,5}
{4,5,6}
MATHEMATICA
Table[Length[Select[Subsets[Range[n]], Intersection[#, Union[Plus@@@Tuples[#, 2], Times@@@Tuples[#, 2]]]=={}&]], {n, 0, 10}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jul 09 2019
EXTENSIONS
a(19)-a(41) from Andrew Howroyd, Aug 25 2019
STATUS
approved