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 A339626 #12 Dec 11 2020 11:36:57
%S A339626 0,0,0,0,3,30,315,4830,96453,2296350
%N A339626 a(n) = A322437(A002110(n)).
%C A339626 For n > 0, a(n) gives the number of unordered pairs of set partitions of {1,...,n} where no block of the other is a subset (or equal) to any block of the other. See A322441.
%F A339626 For n > 0, a(n) = A322441(n)/2.
%e A339626 The a(4) = 3 such (unordered) pairs of set partitions of {1,2,3,4} are:
%e A339626 {{1,2},{3,4}}|{{1,3},{2,4}}
%e A339626 {{1,2},{3,4}}|{{1,4},{2,3}}
%e A339626 {{1,3},{2,4}}|{{1,4},{2,3}}.
%t A339626 Block[{f}, f[n_] := If[n <= 1, {{}}, Join @@ Table[Map[Prepend[#, d] &, Select[f[n/d], Min @@ # >= d &]], {d, Rest[Divisors[n]]}]]; Map[Length[Select[Subsets[f[#], {2}], And[! Or @@ Divisible @@@ #, ! Or @@ Divisible @@@ Reverse /@ #] &@ Tuples[#] &]] &, FoldList[Times, 1, Prime@ Range@ 7]] ] (* _Michael De Vlieger_, Dec 10 2020, after _Gus Wiseman_ at A322437 *)
%Y A339626 Cf. A002110, A322437, A322441.
%K A339626 nonn,more
%O A339626 0,5
%A A339626 _Antti Karttunen_, Dec 10 2020