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Number of 6-element nondividing subsets of {1, 2, ..., n}.
1

%I #11 Feb 16 2025 08:33:14

%S 1,3,4,7,15,27,45,55,85,133,199,262,378,534,803,999,1319,1742,2309,

%T 3007,4020,5166,6565,7950,10380,12882,16533,19664,24099,30912,37550,

%U 44092,54465,65117,79616,94144,111780,132592,159228,187506,219949,256514

%N Number of 6-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="https://mathworld.wolfram.com/NondividingSet.html">Nondividing Set</a>

%e a(31) = 1 because there is one 6-element nondividing subset of {1,2,...,31}: {16,19,23,24,28,31}.

%Y Column 6 of triangle A187489. Cf. A068063.

%K nonn,changed

%O 31,2

%A _Alois P. Heinz_, Mar 10 2011