OFFSET
0,4
COMMENTS
In other words, subsets containing both n and some element that is not the difference of two consecutive elements.
EXAMPLE
The a(1) = 0 through a(6) = 23 subsets:
. . {1,3} {1,4} {1,5} {1,6}
{2,3} {3,4} {2,5} {2,6}
{1,3,4} {3,5} {4,6}
{2,3,4} {4,5} {5,6}
{1,2,5} {1,2,6}
{1,3,5} {1,3,6}
{1,4,5} {1,4,6}
{2,3,5} {1,5,6}
{2,4,5} {2,3,6}
{3,4,5} {2,5,6}
{1,3,4,5} {3,4,6}
{2,3,4,5} {3,5,6}
{4,5,6}
{1,2,5,6}
{1,3,4,6}
{1,3,5,6}
{1,4,5,6}
{2,3,4,6}
{2,3,5,6}
{2,4,5,6}
{3,4,5,6}
{1,3,4,5,6}
{2,3,4,5,6}
MATHEMATICA
Table[Length[Select[Subsets[Range[n]], MemberQ[#, n]&&!SubsetQ[#, Differences[#]]&]], {n, 0, 10}]
CROSSREFS
The complement is counted by A364752.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 06 2023
EXTENSIONS
More terms from Giorgos Kalogeropoulos, Aug 07 2023
STATUS
approved