ASCII Triangle Ripple
GNU sed -nr, 210
A start:
s/1/__/g
p
s#_(.*)_#\\\1/#
s#\\__#\\  #
s#__/#  /#
ta
:a
p
s#(.*) _{6}(_*) # \1\\  \2  /#;ta
s#(.*)  (  )# \1\2#;
s#(.*) _(_*)_ # \1\\\2/#
y/_/ /
Tc
:b
p
:c
s#(.*)((\\)  ( *)(/)|()()()\\/)# \1\3\4\5#;tb

Input is a positive unary integer via STDIN, as per this meta-question.
Output:
$ for i in 1 11 111 1111 11111 111111 1111111; do sed -rnf triripple.sed &lt;&lt;&lt; $i; done
__
\/
 
____
\  /
 \/
  
______
\    /
 \  /
  \/
   
________
\  __  /
 \ \/ /
  \  /
   \/
    
__________
\  ____  /
 \ \  / /
  \ \/ /
   \  /
    \/
     
____________
\  ______  /
 \ \    / /
  \ \  / /
   \ \/ /
    \  /
     \/
      
______________
\  ________  /
 \ \  __  / /
  \ \ \/ / /
   \ \  / /
    \ \/ /
     \  /
      \/
       
$