Originally Posted by

**blablablerg** Dear tonio,

thanks for all your help in the first place.

i was thinking that way about it, but i thought that a sum or product sequence is fixed. correct me if i'm wrong, but i thought that a list whose product is 1, and is increasing, should look like this:

for example:

1/3,1/2,1,2,3

if n-1 you get (by your example)

1/2,1,2,1

this changes the whole list itself, and i always thought that lists used in this way where fixed, and you could only add or remove numbers from the end (n-1, n+1).