If you are stuck with a c-shell and you want to print (or execute a command) for an increment, say of 5,  in a variable (for example, $x), then do either of the following:

#!/bin/csh
# Exammple: 1
foreach x (`seq 1 5 20`)
     echo $x
end
#EOF

#!/bin/csh
# Example: 2
@ x = 1
while ($x <= 20)
     echo $x
@ x += 5
end
#EOF

They both print the numbers 1 to 20 in steps of 5. If you want to use it in the command line, then you need to type each line (of course, except  #!/bin/csh and #EOF) and hit enter .

If you know all the possible elements (numbers, characters or strings) of the array passed on to x for each foreach, then you may  choose to use the following

#!/bin/csh
# Example: 3
foreach x (1 2 9 40)
     echo $x
end
#EOF

when the elements are 1, 2, 9 and 40; or

#!/bin/csh
# Example: 4
foreach x (*.cpp)
     echo $x
end
#EOF

when the elements are all the filenames ending with .cpp in the current directory.

Update: The second option (Example: 2) spits out some syntax error message when used in the command line (in the same way as mentioned above). However, it works fine in a script file.