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%I #10 Sep 26 2015 17:25:24
%S 0,1,2,1,2,3,4,1,2,3,4,3,4,5,6,1,2,3,4,3,4,5,6,3,2,3,2,5,6,7,8,1,2,3,
%T 4,3,4,5,6,3,4,5,6,5,6,7,8,3,4,3,4,3,4,3,4,5,6,7,8,7,8,9,4,1,2,3,4,3,
%U 4,5,6,3,4,5,6,5,6,7,8,3,2,3,4,5,6,7,8,5,6,7,8,7,8,9,10,3,4,5,2,3,4,5,6,3
%N Number of steps to reach 1 starting with n and iterating the map n ->rad(n)-1, where rad(n) is the squarefree kernel of n (A007947).
%C Sequence is defined for all n, as A075423(n) < n.
%H Charles R Greathouse IV, <a href="/A075425/b075425.txt">Table of n, a(n) for n = 1..10000</a>
%o (PARI) rad(n)=vecprod(factor(n)[,1])
%o a(n)=my(k);while(n>1,n=rad(n)-1;k++); k \\ _Charles R Greathouse IV_, Jul 09 2013
%o (Haskell)
%o a075425 n = snd $ until ((== 1) . fst)
%o (\(x, i) -> (a075423 x, i + 1)) (n, 0)
%o -- _Reinhard Zumkeller_, Aug 14 2013
%K nonn
%O 1,3
%A _Reinhard Zumkeller_, Sep 15 2002