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A117358 a(n) = A032742(A032742(A032742(n))) = ((n/lpf(n))/lpf(n/lpf(n)))/lpf((n/lpf(n))/lpf(n/lpf(n))), where lpf=A020639, least prime factor.

%I A117358 #13 Feb 16 2025 08:33:00
%S A117358 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,4,1,1,
%T A117358 1,3,1,1,1,5,1,1,1,1,1,1,1,6,1,1,1,1,1,3,1,7,1,1,1,5,1,1,1,8,1,1,1,1,
%U A117358 1,1,1,9,1,1,1,1,1,1,1,10,3,1,1,7,1,1,1,11,1,5,1,1,1,1,1,12,1,1,1,5,1,1,1
%N A117358 a(n) = A032742(A032742(A032742(n))) = ((n/lpf(n))/lpf(n/lpf(n)))/lpf((n/lpf(n))/lpf(n/lpf(n))), where lpf=A020639, least prime factor.
%H A117358 Antti Karttunen, <a href="/A117358/b117358.txt">Table of n, a(n) for n = 1..65537</a>
%H A117358 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LeastPrimeFactor.html">Least Prime Factor</a>
%F A117358 a(n) = A032742(A032742(A032742(n))) = A032742(A054576(n)) = A054576(n)/A115561(n).
%F A117358 a(A037144(n)) = 1, a(A033987(n)) > 1.
%t A117358 f[n_] := n/FactorInteger[n][[1, 1]]; (* f is A032742 *)
%t A117358 a[n_] := f@ f@ f@ n;
%t A117358 Array[a, 100] (* _Jean-François Alcover_, Dec 09 2021 *)
%t A117358 Table[Nest[#/FactorInteger[#][[1,1]]&,n,3],{n,110}] (* _Harvey P. Dale_, Oct 10 2024 *)
%o A117358 (Scheme) (define (A117358 n) (A032742 (A032742 (A032742 n)))) ;; _Antti Karttunen_, Dec 07 2017
%Y A117358 Cf. A014673, A032742, A037144, A033987, A054576, A115561.
%K A117358 nonn
%O A117358 1,16
%A A117358 _Reinhard Zumkeller_, Mar 10 2006