Here are a few, maybe useful M4 macros, taken from my SunExpert Q&AIX column, January, 1998.

Included are a for loop: for(var,start,end,procedure)

For example,

   for(`x',1,5,`
     x squared = eval(x**2)')  

expands to

     1 squared = 1
     2 squared = 4
     3 squared = 9
     4 squared = 16
     5 squared = 25  

There is also the sublime nextprime calculator, which expands to the next higher prime number from its argument: nextprime(number)

For example,

     nextprime(50000)

expands to

     50021