human
What is a code to friends Pairing Problem and the other steps required given the following:
Friends Pairing Problem | Returns count of ways n people can remain single or paired up ..
Driver code"
How can the above be solved in Python?
assistant
#Here is code to friends Pairing Problem and the other steps required.
 def countFriendsPairings ( n ) :
	a , b , c = 1 , 2 , 0 ;
	if ( n <= 2 ) :
		return n ;
	for i in range ( 3 , n + 1 ) :
		c = b + ( i - 1 ) * a ;
		a = b ;
		b = c ;
	return c ;
n = 4 ;
print ( countFriendsPairings ( n ) ) ;