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 A088810 #25 Feb 16 2025 08:32:51
%S A088810 0,0,0,0,1,4,6,18,35,84,137,323,591,1313,2033,4360,7406,15581,23682,
%T A088810 49184,84017,171744,259818,528784,853143,1727011,2601181,5243126,
%U A088810 8784832,17662987,26541257,53279330,86241323,172871156,259534578,519917139
%N A088810 Number of subsets of {1, ..., n} that are double-free but not sum-free.
%H A088810 Fausto A. C. Cariboni, <a href="/A088810/b088810.txt">Table of n, a(n) for n = 0..88</a>
%H A088810 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Double-FreeSet.html">Double-Free Set</a>
%H A088810 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Sum-FreeSet.html">Sum-Free Set</a>
%H A088810 Reinhard Zumkeller, <a href="/A088808/a088808.txt">Illustration of initial terms</a>
%F A088810 a(n) = A050291(n) - A007865(n) = A088809(n) - A088812(n).
%K A088810 nonn
%O A088810 0,6
%A A088810 _Reinhard Zumkeller_, Oct 19 2003
%E A088810 Terms a(28) and beyond from _Fausto A. C. Cariboni_, Sep 27 2020