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 A275307 #9 Jul 23 2016 20:59:30
%S A275307 1,1,2,44,4983,7565342,2414249587694,56130437054842366160898
%N A275307 Number of labeled spanning blobs on n vertices.
%C A275307 A clutter is a set of sets comprising a connected antichain in the Boolean algebra B_n. A blob is defined as a clutter that cannot be capped by a tree.
%H A275307 Louis J. Billera, <a href="http://dx.doi.org/10.1016/0095-8956(71)90033-5">On the Composition and Decomposition of Clutters</a>, J. Combinatorial Theory 11, 234-245 (1971).
%H A275307 Gus Wiseman, <a href="https://docs.google.com/document/d/1Okx0eXfCCAVM0lbZ2NoFxIJdprOMdBaxZf26Iu-SXSs/pub">Every Clutter is a Tree of Blobs (preprint)</a>
%F A275307 Every clutter is a tree of blobs, so we have A048143(n) = Sum_p n^(k-1) Prod_i a(|p_i|+1), where the sum is over all set partitions U(p_1,...,p_k) = {1,...,n-1}.
%e A275307 The a(3)=2 blobs are: {{1,2,3}}, {{1,2},{1,3},{2,3}}.
%Y A275307 Cf. A048143 (clutters), A030019 (hypertrees), A052888 (tail trees).
%K A275307 nonn,more
%O A275307 1,3
%A A275307 _Gus Wiseman_, Jul 22 2016