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%I #15 Jan 29 2020 04:38:37
%S 1,2,3,2,3,2,3,3,2,3,3,3,2,3,3,3,2,3,3,3,3,2,3,3,3,3,3,2,3,3,3,3,3,2,
%T 3,3,3,3,3,3,2,3,3,3,3,3,3,2,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,2,3,3,3,
%U 3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3,3,3,3,2,3,3,3,3,3,3,3
%N Greatest prime factor of 3-smooth numbers.
%H Amiram Eldar, <a href="/A086411/b086411.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A006530(A003586(n)).
%F A086410(n) <= a(n) <= 3.
%F a(A033845(n)) = A086410(A033845(n))+1; a(A006899(n)) = A086410(A006899(n)). - _Reinhard Zumkeller_, Sep 25 2008
%t Reap[Do[p = FactorInteger[n][[-1, 1]]; If[p < 5, Sow[p]], {n, 1, 2*10^5}] ][[2, 1]] (* _Jean-François Alcover_, Dec 17 2017 *)
%Y Cf. A003586, A006530, A006899, A033845, A086410.
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Jul 18 2003
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