20150513, 16:47  #78  
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
9,161 Posts 
Quote:
Point in case: 4# is correctly parsed as 6, but then, why is 4## = 210 in FactorDB?? 

20150513, 18:49  #79 
Nov 2012
1001000_{2} Posts 
According to the help:
# Primordial (product of all primes below n, postfix) ## Product first n primes (postfix) 4# = 6 4## = 210 (2*3*5*7) (4#)# = 30 seems correct? Last fiddled with by Wick on 20150513 at 18:49 
20150513, 19:23  #80 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
10001111001001_{2} Posts 
1) That's a very "intuitive" design. If you can show how to get this helpful "help"? except as deduced by this comment that it actually exists, and if so, then it just might be at factordb.com/help ... and in fact this page [B]does[/B] exist, in its own world  not linked to any other pages.
2) nobody uses this notation 3) what is 4### then? and why? and what is 4####  is it (4##)## ? (((4#)#)#)# ? ((4#)#)## ? ((4##)#)# ? 
20150514, 03:23  #81  
Jun 2003
7×683 Posts 
FWIW, I just put n## in the search box and looked at the series that factordb printed out.
Of course, the problem is that PFGW interprets ## the same way it inteprets !! (multifactorials), i.e. product of every other prime. Quote:


20150514, 03:48  #82 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
9,161 Posts 
Yes, the PFGW way makes sense. Using ## for something that cannot be written (easily) in another way makes more sense.
Like the motto of a certain method, “To make the impossible possible, the possible easy, and the easy elegant.” Using n## for p_{n}# doesn't make impossible possible, or even possible much easier than it is. If 4## is simply 7# and 10## is simply 29#, then what's the economy? 
20150514, 04:39  #83  
Jun 2003
4781_{10} Posts 
Quote:
Anywho... whatever format it internally supports, it needs to standardise that when communicating with external tools (like PFGW). PS: From factordb.com home page, if you click on the ? link to the right, you'll get the help link. It has page=0 parameter. There are apparently help pages available for 1 & 2 as well 

20150514, 06:32  #84 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
23C9_{16} Posts 
True!
I saw a similar conceptual disconnect at UTM, but in a rare category. I submitted a partition number and all old submissions were in "p(n)" form. But for PFGW, p(n) is the prime number #n, so for a brief moment the prime was deleted (for being too small), then restored again manually by CC. So, anyway, FactorDB's 10## could be represented as p(10)# in PFGW (and could as well be the same in factorDB, if a prefix function p(n) is implemented). Let's see. PFGW has these built in: p(n), Phi(n,x), gcd(x,y), F(n), L(n), and also U(n), V(n) (primitive parts of F(n), L(n)); doesn't have numbpart(), or bernfrac(), or some other things,  for them one can use a bridge from GP to PFGW. FactorDB has only a subset of these. 
20150514, 06:42  #85  
"Antonio Key"
Sep 2011
UK
3^{2}×59 Posts 
Quote:
Consider it's solution to 5# =2*3*5 =30, which should be the same as 4# according to it's definition.. 

20150514, 07:53  #86  
Nov 2012
2^{3}×3^{2} Posts 
Quote:


20150527, 15:50  #87 
Sep 2009
1946_{10} Posts 
Factordb seems unreasonably slow processing primorials. Eg the following two PRPs should be easy to prove prime by N1 but clicking on Primality gets a LONG wait then an incomplete page as if the attempt to calculate how far factored N1 is timed out.
26901*115637#+1 27545*115637#+1 Chris 
20150803, 19:04  #88 
"Daniel Jackson"
May 2011
14285714285714285714
1001100101_{2} Posts 
What's causing the "err" status on certain numbers? It's breaking 9 of the Aliquot sequences. Here's an example (from 270870):
http://factordb.com/index.php?id=1100000000626093582 
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