What are you actually doing with the result? With Maple 2016 you can use Iterator:-Combination to rapidly loop through all results, though the output is expressed as an Array with values from 0 to 19 (rather than 1 to 20). On my machine that takes 0.3 sec. If you need to generate the entire sequence at once, you could do

C := Iterator:-Combination(20,10):
seq({seq(x,x=c+1)}, c = C):

That runs in 1.4 seconds. The expression c+1 increments the results so that they are taken from 1 to 20 rather than 0..19

Consider using combinat:-choose.

It's not clear what you are asking. 

Rather than posting a link to a view of the worksheet, just upload the worksheet here using the up green arrow on the toolbar of this site. A cursory glance at it suggests the conditional will fail because i was never assigned.  What is the purpose of the conditional?

It's not clear why you would need any loop at all.  Posting the equation would be helpful.

Posting an example would be useful.

Does this happen after restarting the Maple kernel? Does it happen in a new Maple session, or only with an existing worksheet?

You might try trapping the error and seeing what led to it.  Do

  stoperror('all');
  time();

If that does trap the error, it will launch the Maple debugger. Inside it, issue the showstat command to see the current procedure and issue the showstack command to see what is on the stack.

@Carl Love Try changing kernelopts(stacklimit).

I don't understand what you are trying to do. 

@Carl Love Note that the user probably want to save the result in .m format, so the file name should have extension .m.  The .mla extension is normally used for Maple archives. The save command does not write to a Maple archive, use savelib for that. Using any extension but .m in a save command results in writing Maple language format rather Mapleinternal format to the text file.

What procedure?  What do you need to debug? 

@tomleslie A minor typo, the open parentheses should be after the tllde.

@nm Semicolons (and colons) are statement separators in Maple syntax. They aren't part of the statement.

What are you trying to achieve?  

@cuongtd Apologies.  I used Maple developer tools (smarch and sload) to build/install mdcs; those are not available.  I have since completely rewritten the Makefile; it no longer uses smarch and sload, but instead some of my own tools that I can distribute but haven't got around to, mainly because they depend on yet other tools I've written and haven't distributed.  What I will do is upload a version of mdcs that can be installed without building.  It might be a few days.