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Re: Concatenation of prime factors of numbers

• To: mathgroup at smc.vnet.net
• Subject: [mg78644] Re: [mg78599] Concatenation of prime factors of numbers
• From: János <janos.lobb at yale.edu>
• Date: Fri, 6 Jul 2007 03:19:08 -0400 (EDT)
• References: <200707050801.EAA01451@smc.vnet.net>

On Jul 5, 2007, at 4:01 AM, 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
>


Here is a newbie approach - without Wikipedia:

In[1]:=
Table[ToExpression[
    StringJoin[
     (If[#1[[2]] == 1,
        ToString[#1[[1]]],
        For[j = 2; a =
           ToString[#1[[1]]],
          j <= #1[[2]], j++,
          a = StringExpression[
           a, ToString[
           #1[[1]]]]];
         a] & ) /@
      FactorInteger[i]]],
   {i, 2, 16}]
Out[1]=
{2, 3, 22, 5, 23, 7, 222, 33,
   25, 11, 223, 13, 27, 35,
   2222}

J=E1nos


-----------------------------------------
A newbie is a newbie is a newbie (even if he has Wikipedia to help him).

- Andrzej Kozlowski

• References:
  • Concatenation of prime factors of numbers
    • From: Diana <diana.mecum@gmail.com>