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Student Support Forum: 'How to create a table of the number of steps?' topicStudent Support Forum > General > Archives > "How to create a table of the number of steps?"

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Author Comment/Response
Bill Simpson
09/21/12 6:30pm

You have a list of things returned from FactorInteger and you want to do the same thing to each thing. That usually meanss "use Map."

Each thing is {primefactor,howmany}. If you had Table[primefactor,{howmany}] this would be close to what you want. Push Map into doing this.

Then use Flatten to merge all the sublists and Plus@@ to total the result.

Now you want to repeatedly do a function to a result until the result stops changing and keep track of how many times you needed to do the function. Length of FixedPointList seems like a good choice.

So

In[1]:= ln[n_]:=Plus@@Flatten[Map[Table[First[#],{Last[#]}]&,FactorInteger[n]]];
Table[Length[FixedPointList[ln,i]]-1,{i,104}]

Out[2]= {2,1,1,1,1,2,1,3,3,2,1,2,1,4,4,4,1,4,1,4,3,2,1,4,3,5,4,2,1,3,1,3,5,2,3,3,1,4,5,2,1,3,1,5,2,4,1,2,5,3,5,2,1,2,5,2,3,2,1,3,1,6,2,3,5,5,1,4,6,5,1,3,1,6,2,2,5,5,1,2,3,2,1,5,3,3,4,2,1,2,5,5,3,6,5,2,1,5,2,5,1,3,1,2}

Compare that with A002217.

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Subject (listing for 'How to create a table of the number of steps?')
Author Date Posted
How to create a table of the number of steps? Jared E 09/21/12 3:43pm
Re: How to create a table of the number of steps? Bill Simpson 09/21/12 6:30pm
Re: How to create a table of the number of steps? Peter Pein 09/24/12 01:51am
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