Draw an ASCII Lightning Bolt Introduction

Partly inspired by this StackOverflow question, let's draw an ASCII Lightning Bolt.

Write a program that takes a positive Integer n via STDIN or command line and outputs the ASCII Lightning Bolt below.

Input

Positive Integer n representing the number of lightning zig-zag tiers to draw.

Example Output

n=1

__
\ \
 \ \
  \ \
   \/


n=2

__
\ \
 \ \
__\ \
\  __\
 \ \
  \ \
   \/


n=3

__
\ \
 \ \
__\ \
\  __\
 \ \
__\ \
\  __\
 \ \
  \ \
   \/


n=4

__
\ \
 \ \
__\ \
\  __\
 \ \
__\ \
\  __\
 \ \
__\ \
\  __\
 \ \
  \ \
   \/


.
.
.
etc



Additional notes


You may write a function that takes n as the only argument and
prints or returns the string.
Trailing spaces and new lines are okay.
No leading spaces except where appropriate for the designated
pattern. 
Shortest code in bytes wins.
Java, 201 196 189 186 182 bytes

Obviously not the best, but it is in Java.



class I{public static void main(String[]a){System.out.print(("__\na a"+new String(new byte[new Byte(a[0])-1]).replace("\0","__a\\  __\\\n a")+"  a   \\/").replace("a","\\ \\\n"));}}