1, 2, 5, 16, 68, 326

Find the wrong number in the given series.

The correct option is 68.

To find the wrong number in the given series: 1, 2, 5, 16, 68, 326, let us analyze the pattern of progression between consecutive terms.

Let the terms of the series be denoted by $T_1,T_2,T_3,T_4,T_5,T_6$.

Let's check the relationship between consecutive terms:
The first term is:
$T_1=1$
To get the second term ($T_2=2$):
$1\times 1+1=2$
To get the third term ($T_3=5$):
$2\times 2+1=5$
To get the fourth term ($T_4=16$):
$5\times 3+1=16$

Following this pattern, the general rule to find the next term is:
$T_n=T_{n-1}\times (n-1)+1$

Applying this rule to find the fifth term:
$T_5=16\times 4+1=64+1=65$
However, the fifth term in the given series is 68.

Let us verify if 65 makes the next term correct:
If the fifth term were 65, the sixth term would be:
$T_6=65\times 5+1=325+1=326$
This matches the sixth term of the series (326) perfectly.

Therefore, the number 68 is incorrect and should be replaced by 65. The wrong number in the series is 68.