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 A304492 #5 May 14 2018 20:22:01
%S A304492 1,2,3,2,4,5,6,3,2,7,8,9,10,11,12,2,13,14,15,16,17,18,19,20,2,21,3,22,
%T A304492 23,24,25,4,26,27,28,2,29,30,31,32,33,34,35,36,37,38,39,40,2,41,42,43,
%U A304492 44,45,46,47,48,49,50,51,52,53,54,5,55,56,57,58,59,60
%N A304492 Position in the sequence of numbers that are not perfect powers (A007916) of the last or deepest exponent in the power-tower for n.
%C A304492 Let {c(i)} = A007916 denote the sequence of numbers > 1 which are not perfect powers. Every positive integer n has a unique representation as a tower n = c(x_1)^c(x_2)^c(x_3)^...^c(x_k), where the exponents are nested from the right. Then a(n) = x_k.
%F A304492 a(n) = A278028(n, A288636(n)).
%t A304492 nn=100;
%t A304492 a[n_]:=If[n==1,1,With[{g=GCD@@FactorInteger[n][[All,2]]},If[g==1,n,a[g]]]];
%t A304492 rads=Union[Array[a,nn]];
%t A304492 Table[a[n],{n,nn}]/.Table[rads[[i]]->i,{i,Length[rads]}]
%Y A304492 Cf. A052409, A052410, A007916, A089723, A164337, A277562, A277564, A278028, A288636, A289023, A294336, A294337, A304481, A304491, A304495.
%K A304492 nonn
%O A304492 1,2
%A A304492 _Gus Wiseman_, May 13 2018