OFFSET
0,2
COMMENTS
Such subsets are called weakly triple-free sets. A050295 is the strongly triple-free analog of this sequence. - Steven Finch, Mar 02 2009
LINKS
Sean A. Irvine, Table of n, a(n) for n = 0..100 (terms 0..61 from Alois P. Heinz)
Steven R. Finch, Triple-Free Sets of Integers [From Steven Finch, Apr 20 2019]
Sean A. Irvine, Java program (github)
EXAMPLE
a(6) = 50. There are 64 subsets of {1, 2, 3, 4, 5, 6}. We exclude the 8 that contain {1, 2, 3} and the 8 that contain {2, 4, 6}. We've double-counted the 2 that contain {1, 2, 3, 4, 6}. This yields 64 - 8 - 8 + 2 = 50.
CROSSREFS
KEYWORD
nonn
AUTHOR
David Wasserman, Feb 14 2002
EXTENSIONS
a(33)-a(34) from Alois P. Heinz, Jan 17 2019
STATUS
approved