human
Counting pairs when a person can form pair with at most one | Number of ways in which participant can take part ..
Base condition.
A participant can choose to consider ( 1 ) Remains single . Number of people reduce to ( x - 1 ) ( 2 ) Pairs with one of the ( x - 1 ) others . For every pairing , number of people reduce to ( x - 2 ) ..
Driver code"
Solution in Python:

Can you provide a code to counting pairs when a person can form pair with at most one and the other steps required?
assistant
#Here is code to counting pairs when a person can form pair with at most one and the other steps required.
 def numberOfWays ( x ) :
	if x == 0 or x == 1 :
		return 1
	else :
		return ( numberOfWays ( x - 1 ) + ( x - 1 ) * numberOfWays ( x - 2 ) )
x = 3
print ( numberOfWays ( x ) )