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 A117181 #17 Feb 11 2021 03:56:48
%S A117181 4,8,9,4,16,9,5,8,25,27,7,32,9,8,11,9,16,49,25,13,27,8,5,9,64,17,9,25,
%T A117181 19,16,81,7,11,9,23,32,49,11,25,13,27,16,29,13,8,121,31,125,9,128,11,
%U A117181 27,17,7,16,49,37,25,19,17,13,32,81,41,8,169,19,43,25,16,9,23,47,27,64,49
%N A117181 Highest prime-power dividing the n-th nonsquarefree positive integer.
%C A117181 a(n) is prime at 7, 11, ...
%H A117181 Amiram Eldar, <a href="/A117181/b117181.txt">Table of n, a(n) for n = 1..10000</a>
%F A117181 a(n) = A034699(A013929(n)).
%e A117181 12, the 4th nonsquarefree positive integer, is 2^2 * 3. 2^2 = 4 is the largest prime power dividing 12. So a(4) = 4.
%p A117181 A013929 := proc(nmax) local a,n ; a := [] ; n :=1 ; while nops(a) < nmax do if not numtheory[issqrfree](n) then a := [op(a),n] ; fi ; n := n+1 ; od ; a ; end : A034699 := proc(n) local ifs,res; if n = 1 then 1 ; else ifs := ifactors(n)[2] ; seq(op(1,op(i,ifs))^op(2,op(i,ifs)), i=1..nops(ifs)) ; max(%) ; fi ; end: a013929 := A013929(200) : for n from 1 to nops(a013929) do printf("%d, ",A034699(op(n,a013929))) ; od ; # _R. J. Mathar_, May 10 2007
%t A117181 s[n_] := Max @@ Power @@@ FactorInteger[n]; s /@ Select[Range[200], !SquareFreeQ[#] &] (* _Amiram Eldar_, Feb 11 2021 *)
%Y A117181 Cf. A034699, A013929, A117180, A117182.
%K A117181 nonn
%O A117181 1,1
%A A117181 _Leroy Quet_, Mar 01 2006
%E A117181 More terms from _R. J. Mathar_, May 10 2007