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 A304999 #23 May 02 2025 01:27:19
%S A304999 1,1,5,53,1577,212137,496946349,309068823607069,
%T A304999 14369391923126237496803793,
%U A304999 146629927766168786109802623629262590838145873
%N A304999 Number of labeled antichains of finite sets spanning n vertices with singleton edges allowed.
%C A304999 Only the non-singleton edges are required to form an antichain.
%H A304999 Aniruddha Biswas and Palash Sarkar, <a href="https://arxiv.org/abs/2304.14069">Counting unate and balanced monotone Boolean functions,</a> arXiv:2304.14069 [math.CO], 2023.
%H A304999 Aniruddha Biswas and Palash Sarkar, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL28/Biswas/biswas6.html">Counting Unate and Monotone Boolean Functions Under Restrictions of Balancedness and Non-Degeneracy</a>, J. Int. Seq. (2025) Vol. 28, Art. No. 25.3.4. See p. 4.
%H A304999 Gus Wiseman, <a href="/A048143/a048143_4.txt">Sequences enumerating clutters, antichains, hypertrees, and hyperforests, organized by labeling, spanning, and allowance of singletons</a>.
%F A304999 Exponential transform of A304985.
%F A304999 Inverse binomial transform of A305000. - _Aniruddha Biswas_, May 12 2024
%e A304999 The a(2) = 5 antichains:
%e A304999 {{1,2}}
%e A304999 {{1},{2}}
%e A304999 {{1},{1,2}}
%e A304999 {{2},{1,2}}
%e A304999 {{1},{2},{1,2}}
%Y A304999 Cf. A006126, A014466, A261005, A304996, A304997, A304998, A304999, A305000, A305001.
%Y A304999 Cf. A000372, A003182, A304985, A305844, A306505, A319721, A321679, A324167.
%K A304999 nonn,more
%O A304999 0,3
%A A304999 _Gus Wiseman_, May 23 2018
%E A304999 a(5)-a(8) from _Gus Wiseman_, May 31 2018
%E A304999 a(9) from _Aniruddha Biswas_, May 12 2024