Greatest and Least Prime Factors

[David Wasserman]

On Aug 30, 2006, at 8:54 AM, franktaw at netscape.net wrote:

>
> As for always spelling it out, this will never apply in formulas.  We
> always define a shorter name, and then use that in the formula.
> The question is, what shorter name should be used?
>

Usually it's best to use a single-letter name. For example, A072268  
could be rewritten "Let a(n+1)=1+f(a(n))^2, where f(x) is the largest  
prime factor of x (A006530)." Multi-letter symbols are dangerous  
because we use concatenation to show multiplication, so lpf(n) could  
be read as l times p times f(n). Also note that I wrote f(x) instead  
of f(n). n is the independent variable of the sequence, and I think  
it's confusing to use it for anything else.

I think we should use multi-letter function names only for the  
functions listed at http://www.research.att.com/~njas/sequences/ 
FAQ.html#Z08. Maybe a few more functions could be added to this list,  
but I don't think largest prime factor and least prime factor are  
important enough to have abbreviations. Right now I can't think of  
anything that should be added.

  - David