(321+581)n
General term Tr+1=Crn(321)n−r(581)r
Tr+1=Crn32n−r58r.
2n−r,8r must be integer.
2n−r∈I⇒n−r=0,2,4,6,8.......
8r∈I⇒r=0,8,16,24,32....
For rational term common powers=0,8,16,24.......
Number of integral term=33
Ts=a+(s−1)d⇒T33=0+(33−1)8=256.
Value of n=256.
We can cross check to verify answer.