Loop of length 20 starting with a string of length 8
found after enumerating 54423 derivations:

.ab.bbbbbb
	rule ab -> bbca at position 0
.bbca.bbbbbb
	rule ab -> bbca at position 3
.bbcbbca.bbbbb
	rule b ->  at position 3
.bbcbca.bbbbb
	rule b ->  at position 3
.bbcca.bbbbb
	rule ab -> bbca at position 4
.bbccbbca.bbbb
	rule ccb -> a at position 2
.bbabca.bbbb
	rule ab -> bbca at position 5
.bbabcbbca.bbb
	rule b ->  at position 5
.bbabcbca.bbb
	rule b ->  at position 5
.bbabcca.bbb
	rule ab -> bbca at position 6
.bbabccbbca.bb
	rule ccb -> a at position 4
.bbababca.bb
	rule ab -> bbca at position 4
.bbabbbcaca.bb
	rule a ->  at position 7
.bbabbbcca.bb
	rule ab -> bbca at position 8
.bbabbbccbbca.b
	rule ccb -> a at position 6
.bbabbbabca.b
	rule ab -> bbca at position 6
.bbabbbbbcaca.b
	rule a ->  at position 9
.bbabbbbbcca.b
	rule ab -> bbca at position 10
.bbabbbbbccbbca.
	rule ccb -> a at position 8
.bbabbbbbabca.
	rule ab -> bbca at position 8
.bbabbbbbbbcaca.