%I #9 Mar 09 2018 12:20:59

%S 2,4,6,11,15,24,50,83,127,209,310,431,679,921,1229,1624,2145,2770,

%T 3752,4866,6141,7753,9679,12005,15027,18134,22045,26368,31712,37763,

%U 45569,53810,63393,73560,86496,100071,117234,134623,155465,176876

%N Number of 5-element nondividing subsets of {1, 2, ..., n}.

%C A set is called nondividing if no element divides the sum of any nonempty subset of the other elements.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/NondividingSet.html">Nondividing Set</a>

%e a(21) = 2 because there are two 5-element nondividing subsets of {1,2,...,21}: {12,16,18,19,21}, {12,14,18,20,21}.

%Y Column 5 of triangle A187489. Cf. A068063.

%K nonn

%O 21,1

%A _Alois P. Heinz_, Mar 10 2011