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 A326083 #16 Mar 24 2022 17:34:50 %S A326083 1,2,3,5,7,12,16,27,37,58,80,131,171,277,380,580,785,1250,1655,2616, %T A326083 3516,5344,7257,11353,14931,23204,31379,47511,63778,98681,130503, %U A326083 201357,270038,407429,548090,840171,1110429,1701872,2284325,3440337,4601656 %N A326083 Number of subsets of {1..n} containing all of their pairwise sums <= n. %C A326083 The summands are allowed to be equal. The case where they must be distinct is A326080. If A007865 counts sum-free sets, this sequence counts sum-closed sets. This is different from sum-full sets (A093971). %C A326083 From _Gus Wiseman_, Jul 08 2019: (Start) %C A326083 Also the number of subsets of {1..n} containing no sum of any multiset of the elements. For example, the a(0) = 1 through a(6) = 16 subsets are: %C A326083 {} {} {} {} {} {} {} %C A326083 {1} {1} {1} {1} {1} {1} %C A326083 {2} {2} {2} {2} {2} %C A326083 {3} {3} {3} {3} %C A326083 {2,3} {4} {4} {4} %C A326083 {2,3} {5} {5} %C A326083 {3,4} {2,3} {6} %C A326083 {2,5} {2,3} %C A326083 {3,4} {2,5} %C A326083 {3,5} {3,4} %C A326083 {4,5} {3,5} %C A326083 {3,4,5} {4,5} %C A326083 {4,6} %C A326083 {5,6} %C A326083 {3,4,5} %C A326083 {4,5,6} %C A326083 (End) %H A326083 Fausto A. C. Cariboni, <a href="/A326083/b326083.txt">Table of n, a(n) for n = 0..100</a> %F A326083 For n > 0, a(n) = A103580(n) + 1. %e A326083 The a(0) = 1 through a(6) = 16 subsets: %e A326083 {} {} {} {} {} {} {} %e A326083 {1} {2} {2} {3} {3} {4} %e A326083 {1,2} {3} {4} {4} {5} %e A326083 {2,3} {2,4} {5} {6} %e A326083 {1,2,3} {3,4} {2,4} {3,6} %e A326083 {2,3,4} {3,4} {4,5} %e A326083 {1,2,3,4} {3,5} {4,6} %e A326083 {4,5} {5,6} %e A326083 {2,4,5} {2,4,6} %e A326083 {3,4,5} {3,4,6} %e A326083 {2,3,4,5} {3,5,6} %e A326083 {1,2,3,4,5} {4,5,6} %e A326083 {2,4,5,6} %e A326083 {3,4,5,6} %e A326083 {2,3,4,5,6} %e A326083 {1,2,3,4,5,6} %e A326083 The a(7) = 27 subsets: %e A326083 {} {4} {36} {246} {2467} {24567} {234567} {1234567} %e A326083 {5} {45} {356} {3467} {34567} %e A326083 {6} {46} {367} {3567} %e A326083 {7} {47} {456} {4567} %e A326083 {56} {457} %e A326083 {57} {467} %e A326083 {67} {567} %t A326083 Table[Length[Select[Subsets[Range[n]],SubsetQ[#,Select[Plus@@@Tuples[#,2],#<=n&]]&]],{n,0,10}] %Y A326083 Cf. A007865, A050291, A051026, A054519, A085489, A093971, A103580, A120641, A151897, A326020, A326023, A326076, A326080. %K A326083 nonn %O A326083 0,2 %A A326083 _Gus Wiseman_, Jun 05 2019