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 A364841 #10 Oct 18 2023 04:54:16 %S A364841 1,2,3,6,9,15,21,34,49,75,105 %N A364841 Number of subsets S of {1..n} containing no element equal to the sum of a k-multiset of elements of S, for any 2 <= k <= |S|. %e A364841 The a(0) = 1 through a(5) = 15 subsets: %e A364841 {} {} {} {} {} {} %e A364841 {1} {1} {1} {1} {1} %e A364841 {2} {2} {2} {2} %e A364841 {3} {3} {3} %e A364841 {1,3} {4} {4} %e A364841 {2,3} {1,3} {5} %e A364841 {1,4} {1,3} %e A364841 {2,3} {1,4} %e A364841 {3,4} {1,5} %e A364841 {2,3} %e A364841 {2,5} %e A364841 {3,4} %e A364841 {3,5} %e A364841 {4,5} %e A364841 {3,4,5} %t A364841 Table[Length[Select[Subsets[Range[n]], Intersection[#,Join@@Table[Total/@Tuples[#,k], {k,2,Length[#]}]]=={}&]],{n,0,10}] %Y A364841 Cf. A007865, A085489, A103580, A151897, A236912, A326020, A326080, A326083, A364349, A364534. %K A364841 nonn,more %O A364841 0,2 %A A364841 _Gus Wiseman_, Aug 15 2023