@Carl Love Here's my one-line minimal-arithmetic while loop. This uses Maple 2019 syntax:

{((b,a):= (0,1)), (while (s:= a+b) < 10000 do (a,b):= (s,a); if issqr(a) then a fi od)};

It was proven in 1964 that the only square Fibonacci numbers are 0, 1, and 144. See: Cohn, JHE (1964), "Square Fibonacci Numbers etc", Fibonacci Quarterly, 2: 109-13. The proof there is not exceedingly difficult.
 

@Stretto Regarding "collecting" on the strings: In my Answer, I provided a method for the mathematical evaluation (through the value command) of the colored output. Acer also gave a similar method. If that's not sufficient for your needs, then you'll need to be more explicit about what you mean by "collecting". The key component of these evaluations is the command Typesetting:-Parse. 

@suvetha2000 Apology accepted, and I'm available if you want to continue working on this problem.

I figured it out! The axis order is set by the DEplot3d command. Where you have [z(t), y(t), x(t)], you should make it [x(t), y(t), z(t)]. 

@Carl Love Sorry, the parabola is not showing up in that plot! I don't know why. It'll take me a little while to figure it out.

@goli You simply need to terminate the display command with a semicolon rather than a colon. The purpose of the colon is to suppress the output, which in this case is the plot itself.

display(a1, a2);

@goli Sorry, but I don't know the first thing about copy-and-pasting. I do all my work programmatically. Plots can be merged using the command plots:-display. There's probably a way to do it with copy-and-paste; I just know nothing about it except that it leads to corruption, moral decay, and irreproducible results; it's antithetical to the scientific method.

@vv Yes, that's what I meant. Note that all code in seq, add, and mul statements is invoked for every index value.

Alias allows an existing rtable to be indexed in a different way, without copying it. So it's not quite correct to say that it creates a 2x2 Matrix. Rather, it allows the 1-D Array created inside the Iterator to be indexed as a Matrix. 

@vv It's not quite the same thing, although it may ultimately produce the same output. The point of my form is to avoid repeated calls to Alias.

@Stretto Maple's normal order of evaluation---used in the vast majority of cases---is from the inside to the outside. This can be changed by procedures that declare parameters as uneval. This should be used rarely, and with caution. EV must be such a procedure. I am not familiar with it. What is it?

This works fine:

Color(ithprime(5));

I get a green 11.

Your Wirth syntax diagram for the second form (the in form) is incorrect: The for clause is actually optional. Here's how that can be used in practice:

M:= ArrayTools:-Alias(output((J:= Iterator:-Combination(6,4))), 0, [2,2]):
(in J do M+~1 od); 
 

Please post an example of that, and please indicate your Maple version. You can post a worksheet using the green uparrow on the MaplePrimes editor toolbar.

@Carl Love My experience with Feedly so far is that

1. There's a lag of about an hour before messages appear on it;
2. I can't find any option for it to send notifications, i.e., to make my phone beep. 

It seems that you intended to attach a worksheet, but there's none attached. Please try again.

@Scot Gould Thanks, I will try Feedly. At this point, I know so little about this that I couldn't tell you if it's what I want. I realized that I'd get some spam notifications also, but that's okay since I'm one of the people who deletes them.