_ nmmn _ mmnn _ mnnm _

The series is abb/aaabbb/aaaabbbb/a. Thus the letters are repeated twice, then thrice, then four times and so on.

The series is aba/aba/aba/aba. Thus, the pattern 'aba' is repeated.

The series is abc/bca/cab/abc/bca, Thus, the letters change places in a cyclic order.

The series is babc/babc/babc. Thus, the pattern 'babc' is repeated.

The series is cabbac/cabbac/cabbac. Thus, the pattern 'cabbac' is repeated.

The series is abncb/abncb/abncb. Thus, the pattern 'abncb' is repeated.

The series is abb/abb/abb/abb. Thus, the pattern 'abb' is repeated.

The series is ccc bbb aaa/ccc bbb aaa/c. Thus, the pattern ccc bbb aaa is repeated.

The series is bcaa/bcaa/bcaa/bcaa. Thus, the pattern 'bcaa' is repeated.

The series is abadna/abadna/abadna/ab. Thus, the pattern 'abadna' is repeated.