OFFSET
0,7
COMMENTS
A binary index of n is any position of a 1 in its reversed binary expansion. The binary indices of n are row n of A048793.
EXAMPLE
The a(0) = 0 through a(7) = 23 subsets:
. . . . . {2,3,4,5} {2,4,6} {2,4,6}
{2,3,4,5} {2,3,4,5}
{2,3,4,6} {2,3,4,6}
{2,3,5,6} {2,3,4,7}
{2,4,5,6} {2,3,5,6}
{3,4,5,6} {2,3,5,7}
{2,3,4,5,6} {2,3,6,7}
{2,4,5,6}
{2,4,5,7}
{2,4,6,7}
{2,5,6,7}
{3,4,5,6}
{3,4,5,7}
{3,4,6,7}
{3,5,6,7}
{4,5,6,7}
{2,3,4,5,6}
{2,3,4,5,7}
{2,3,4,6,7}
{2,3,5,6,7}
{2,4,5,6,7}
{3,4,5,6,7}
{2,3,4,5,6,7}
MATHEMATICA
bpe[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];
Table[Length[Select[Subsets[Range[2, n]], Select[Tuples[bpe/@#], UnsameQ@@#&]=={}&]], {n, 0, 10}]
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Mar 10 2024
STATUS
approved