OFFSET
7,2
COMMENTS
A set is called nondividing if no element divides the sum of any nonempty subset of the other elements.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 7..200
Eric Weisstein's World of Mathematics, Nondividing Set.
EXAMPLE
a(7) = 1 because there is one 3-element nondividing subset of {1,2,3,4,5,6,7}: {4,6,7}.
a(9) = 6: {4,6,7}, {4,6,9}, {5,6,8}, {5,8,9}, {6,7,9}, {6,8,9}.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 10 2011
STATUS
approved