a _ b _ ca _ b _ c _ a _ cc

The given letter series in below pattern.
ccba
Using the same pattern, we will get complete letter series.
ccba/ b b ca/ a a bc/ cc b a/ b

As per given question, the letter series is following the below pattern.
a b c d d
After using the pattern the complete letter series will be as below.
a b c d d/ a b c c d/ a b b c d/ a

In each subsequent term the last letter becomes the first letter.
Using the same pattern, we will get next term of given letter series.
bcde ebcd debc cdeb bcde

As per given question, the letter series is following the below pattern.
a b a b c
After using the pattern the complete letter series will be as below.
a b a b c /bc bc a/ caca b

Here the letter series is as follows :-
ncd/ dcn
After using the pattern the complete letter series will be as below.
ncd / dcn / ccd / dcn / ndd / dcn / ndd

The pattern of given letter series is :-
b a a c
After completing the pattern, we will get complete letter series.
b a a c/ a c c b/ c b b a/ b a a c

The pattern of given letter series is :-
a b b
After completing the pattern, we will get complete letter series.
a b b/ a b b/ b a a/ a b b

As per given question, the letter series is following the below pattern.
a b b a
Using the same pattern, we will get complete letter series.
a b b a/ a b b a/ a b b a

As per given question, the letter series is following the below pattern.
a b a b a b
After using the pattern the complete letter series will be as below.
a b a b a b/ a b a b a b

The given letter series in below pattern.
B R O W N
Using the same pattern, we will get complete letter series.
B R O W N/B R O W N/B