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 A329556 #5 Nov 18 2019 08:48:39
%S A329556 1,2,26,754,32422,1523834
%N A329556 Smallest MM-number of a set of n sets with no singletons.
%C A329556 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798. The multiset of multisets with MM-number n is formed by taking the multiset of prime indices of each part of the multiset of prime indices of n. For example, the prime indices of 78 are {1,2,6}, so the multiset of multisets with MM-number 78 is {{},{1},{1,2}}.
%e A329556 The sequence of terms together with their corresponding systems begins:
%e A329556 1: {}
%e A329556 2: {{}}
%e A329556 26: {{},{1,2}}
%e A329556 754: {{},{1,2},{1,3}}
%e A329556 32422: {{},{1,2},{1,3},{1,4}}
%e A329556 1523834: {{},{1,2},{1,3},{1,4},{2,3}}
%t A329556 primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
%t A329556 dae=Select[Range[100000],SquareFreeQ[#]&&And@@SquareFreeQ/@primeMS[#]&&FreeQ[primeMS[#],_?PrimeQ]&];
%t A329556 Table[dae[[Position[PrimeOmega/@dae,k][[1,1]]]],{k,First[Split[Union[PrimeOmega/@dae],#2==#1+1&]]}]
%Y A329556 MM-numbers of sets of sets with no singletons are A329630.
%Y A329556 The case without empty edges is A329554.
%Y A329556 MM-numbers of sets of sets are A302494.
%Y A329556 Cf. A056239, A112798, A302242, A329552, A329557, A329558.
%Y A329556 Classes of MM-numbers: A305078 (connected), A316476 (antichains), A318991 (chains), A320456 (covers), A329559 (clutters).
%K A329556 nonn,more
%O A329556 0,2
%A A329556 _Gus Wiseman_, Nov 17 2019