A075425 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).

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, 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, 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

Offset

1,3

Comments

Sequence is defined for all n, as A075423(n) < n.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Prog

(PARI) rad(n)=vecprod(factor(n)[, 1])
a(n)=my(k); while(n>1, n=rad(n)-1; k++); k \\ Charles R Greathouse IV, Jul 09 2013
(Haskell)
a075425 n = snd $ until ((== 1) . fst)
                        (\(x, i) -> (a075423 x, i + 1)) (n, 0)
-- Reinhard Zumkeller, Aug 14 2013

Crossrefs

Sequence in context: A194841 A194911 A194865 * A330960 A327189 A255045

Adjacent sequences: A075422 A075423 A075424 * A075426 A075427 A075428

Keyword

nonn

Author

Reinhard Zumkeller, Sep 15 2002

Status

approved