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 A326908 #4 Aug 04 2019 19:10:43
%S A326908 2,4,9,23,70,256,1160,6599,48017,452518,5574706,90198548,1919074899,
%T A326908 53620291147,1962114118390,93718030190126,5822768063787557
%N A326908 Number of non-isomorphic sets of subsets of {1..n} that are closed under union and intersection.
%e A326908 Non-isomorphic representatives of the a(0) = 2 through a(3) = 23 sets of subsets:
%e A326908 {} {} {} {}
%e A326908 {{}} {{}} {{}} {{}}
%e A326908 {{1}} {{1}} {{1}}
%e A326908 {{}{1}} {{12}} {{12}}
%e A326908 {{}{1}} {{}{1}}
%e A326908 {{}{12}} {{123}}
%e A326908 {{2}{12}} {{}{12}}
%e A326908 {{}{2}{12}} {{}{123}}
%e A326908 {{}{1}{2}{12}} {{2}{12}}
%e A326908 {{3}{123}}
%e A326908 {{}{2}{12}}
%e A326908 {{23}{123}}
%e A326908 {{}{3}{123}}
%e A326908 {{}{23}{123}}
%e A326908 {{}{1}{2}{12}}
%e A326908 {{3}{23}{123}}
%e A326908 {{}{1}{23}{123}}
%e A326908 {{}{3}{23}{123}}
%e A326908 {{3}{13}{23}{123}}
%e A326908 {{}{2}{3}{23}{123}}
%e A326908 {{}{3}{13}{23}{123}}
%e A326908 {{}{2}{3}{13}{23}{123}}
%e A326908 {{}{1}{2}{3}{12}{13}{23}{123}}
%t A326908 Table[Length[Select[Subsets[Subsets[Range[n]]],SubsetQ[#,Union@@@Tuples[#,2]]&&SubsetQ[#,Intersection@@@Tuples[#,2]]&]],{n,0,3}]
%Y A326908 The labeled version is A306445.
%Y A326908 Taking first differences and prepending 1 gives A326898.
%Y A326908 Taking second differences and prepending two 1's gives A001930.
%Y A326908 Cf. A000612, A000798, A003180, A108798, A108800, A193675, A326867, A326876, A326878, A326882, A326883.
%K A326908 nonn,more
%O A326908 0,1
%A A326908 _Gus Wiseman_, Aug 03 2019