% cat times.m4
 changequote([,])
 define(times2,[ifelse($1,$2,$3,
    [times2(incr($1),$2,$3)$3])])
 define(times,[times2(1,$1,$2)])
 times(4,[<br>])
 % m4 times.m4
 <br><br><br><br>
 %