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 A316494 #8 Jul 05 2018 02:30:51
%S A316494 1,2,3,5,6,10,11,13,15,22,26,29,30,31,33,41,47,55,58,62,66,79,82,93,
%T A316494 94,101,109,110,113,123,127,137,141,143,145,155,158,165,179,186,202,
%U A316494 205,211,218,226,246,254,257,271,274,282,286,290,293,310,317,327,330
%N A316494 Matula-Goebel numbers of locally disjoint rooted identity trees, meaning no branch overlaps any other branch of the same root.
%C A316494 A prime index of n is a number m such that prime(m) divides n. A number is in the sequence iff either it is equal to 1, it is a prime number whose prime index already belongs to the sequence, or its prime indices are pairwise coprime, distinct, and already belong to the sequence.
%e A316494 The sequence of all locally disjoint rooted identity trees preceded by their Matula-Goebel numbers begins:
%e A316494 1: o
%e A316494 2: (o)
%e A316494 3: ((o))
%e A316494 5: (((o)))
%e A316494 6: (o(o))
%e A316494 10: (o((o)))
%e A316494 11: ((((o))))
%e A316494 13: ((o(o)))
%e A316494 15: ((o)((o)))
%e A316494 22: (o(((o))))
%e A316494 26: (o(o(o)))
%e A316494 29: ((o((o))))
%e A316494 30: (o(o)((o)))
%e A316494 31: (((((o)))))
%t A316494 primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
%t A316494 Select[Range[1000],Or[#==1,And[SquareFreeQ[#],Or[PrimeQ[#],CoprimeQ@@primeMS[#]],And@@#0/@primeMS[#]]]&]
%Y A316494 Cf. A000081, A004111, A007097, A276625, A277098, A302696, A303362, A304713, A316467, A316471, A316474, A316495.
%K A316494 nonn
%O A316494 1,2
%A A316494 _Gus Wiseman_, Jul 04 2018