OFFSET

0,2

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.

LINKS

EXAMPLE

The a(0) = 1 through a(4) = 14 subsets:

{} {} {} {} {}

{1} {1} {1} {1}

{2} {2} {2}

{1,2} {3} {3}

{1,2} {4}

{1,3} {1,2}

{2,3} {1,3}

{1,4}

{2,3}

{2,4}

{3,4}

{1,2,4}

{1,3,4}

{2,3,4}

MATHEMATICA

bpe[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];

Table[Length[Select[Subsets[Range[n]], Select[Tuples[bpe/@#], UnsameQ@@#&]!={}&]], {n, 0, 10}]

CROSSREFS

KEYWORD

nonn

AUTHOR

Gus Wiseman, Mar 08 2024

EXTENSIONS

a(19)-a(40) from Alois P. Heinz, Mar 09 2024

STATUS

approved