divert(-1)
# forloop(i, from, to, stmt)

define(`forloop', `pushdef(`$1', `$2')_forloop(`$1', `$2', `$3', `$4')popdef(`$1')')
define(`_forloop',
       `$4`'ifelse($1, `$3', ,
			 `define(`$1', incr($1))_forloop(`$1', `$2', `$3', `$4')')')
divert
forloop(`x', 1, 100, `2**x = eval(2**x)
')