Pattern in Alternate/Adjacent numbers:This is a complex series in which the successive letters decrease or multiplied by ... Thus, the number in the blank will be
Here in the above series the alphabets are arranged in sequence from last to first. i.e. B,C,D,_,F. So the missing letter in the above is E. Also The numbers are 2,_,8,16,32 In the above the previous number is multiplied to get next number. So the missing letter is 4. Therefore the missing series is E4.