A348481 a(n) is the number of n-element subsets of {1,2,3,...,A347498(n)} with the property that all products i * j are distinct for i <= j.

1, 1, 1, 3, 1, 1, 1, 5, 15, 6, 12, 45, 2, 65, 4, 4, 4, 44, 2, 392

Offset

1,4

Links

Table of n, a(n) for n=1..20.

Example

For n = 8, A347498(n) = 11, and the a(8) = 5 8-element subsets of {1,2,...,11} with distinct pairwise products are
{1,2,5,6,7,8,9,11};
{1,2,6,7,8,9,10,11};
{1,5,6,7,8,9,10,11};
{2,3,5,7,8,9,10,11}; and
{2,5,6,7,8,9,10,11}.

Crossrefs

Cf. A347498, A347499.

Sequence in context: A300853 A293012 A341033 * A274391 A368862 A339768

Adjacent sequences: A348478 A348479 A348480 * A348482 A348483 A348484

Keyword

nonn,more

Author

Peter Kagey, Oct 20 2021

Extensions

a(18)-a(20) from Michael S. Branicky, Oct 28 2021

Status

approved