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 A187493 #11 Feb 16 2025 08:33:14
%S A187493 1,3,4,7,15,27,45,55,85,133,199,262,378,534,803,999,1319,1742,2309,
%T A187493 3007,4020,5166,6565,7950,10380,12882,16533,19664,24099,30912,37550,
%U A187493 44092,54465,65117,79616,94144,111780,132592,159228,187506,219949,256514
%N A187493 Number of 6-element nondividing subsets of {1, 2, ..., n}.
%C A187493 A set is called nondividing if no element divides the sum of any nonempty subset of the other elements.
%H A187493 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/NondividingSet.html">Nondividing Set</a>
%e A187493 a(31) = 1 because there is one 6-element nondividing subset of {1,2,...,31}: {16,19,23,24,28,31}.
%Y A187493 Column 6 of triangle A187489. Cf. A068063.
%K A187493 nonn
%O A187493 31,2
%A A187493 _Alois P. Heinz_, Mar 10 2011