This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A187550 #9 Feb 16 2025 08:33:14
%S A187550 2,3,4,5,6,9,12,15,19,24,35,46,60,83,102,135
%N A187550 Number of 8-element nondividing subsets of {1, 2, ..., n}.
%C A187550 A set is called nondividing if no element divides the sum of any nonempty subset of the other elements.
%H A187550 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/NondividingSet.html">Nondividing Set</a>
%e A187550 a(65) = 2 because there are two 8-element nondividing subsets of {1,2,...,65}: {36,40,48,49,53,61,64,65}, {30,44,45,49,50,59,64,65}.
%Y A187550 Column 8 of triangle A187489. Cf. A068063.
%K A187550 nonn,more
%O A187550 65,1
%A A187550 _Alois P. Heinz_, Mar 11 2011