Re: Concatenation of prime factors of numbers
- To: mathgroup at smc.vnet.net
- Subject: [mg78672] Re: Concatenation of prime factors of numbers
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 6 Jul 2007 03:33:41 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <f6i940$1mj$1@smc.vnet.net>
Diana wrote:
> Can someone help me with this trick?
>
> I would like to create the following sequence, based on FactorInteger:
>
> 2,3,22,5,23,7,222,33,25,11,223,13,27,35,2222, ...
>
> where each term is the concatenation of the prime factors of n.
>
> Thanks,
>
> Diana
Hi Diana,
The following expressions will do what you are looking for:
In[1]:=
expnd[{fac_, exp_}] := StringJoin @@ Table[ToString[fac], {exp}]
concat[lst_] := ToExpression[StringJoin[expnd /@ lst]]
seq = Table[FactorInteger[n], {n, 2, 16}];
concat /@ seq
Out[4]=
{2, 3, 22, 5, 23, 7, 222, 33, 25, 11, 223, 13, 27, 35, 2222}
Regards,
Jean-Marc