Loop of length 21 starting with a string of length 13
found after enumerating 36422 derivations:

.cbbb.bbbbbbbbb
	rule cbbb -> aacc at position 0
.aacc.bbbbbbbbb
	rule cbbb -> aacc at position 3
.aacaacc.bbbbbb
	rule a -> bb at position 3
.aacbbacc.bbbbbb
	rule a -> bb at position 5
.aacbbbbcc.bbbbbb
	rule cbbb -> aacc at position 8
.aacbbbbcaacc.bbb
	rule a -> bb at position 8
.aacbbbbcbbacc.bbb
	rule a -> bb at position 10
.aacbbbbcbbbbcc.bbb
	rule cbbb -> aacc at position 7
.aacbbbbaaccbcc.bbb
	rule a -> bb at position 7
.aacbbbbbbaccbcc.bbb
	rule a -> bb at position 9
.aacbbbbbbbbccbcc.bbb
	rule cbbb -> aacc at position 15
.aacbbbbbbbbccbcaacc.
	rule a -> bb at position 15
.aacbbbbbbbbccbcbbacc.
	rule a -> bb at position 17
.aacbbbbbbbbccbcbbbbcc.
	rule cbbb -> aacc at position 14
.aacbbbbbbbbccbaaccbcc.
	rule a -> bb at position 14
.aacbbbbbbbbccbbbaccbcc.
	rule cbbb -> aacc at position 12
.aacbbbbbbbbcaaccaccbcc.
	rule a -> bb at position 12
.aacbbbbbbbbcbbaccaccbcc.
	rule a -> bb at position 14
.aacbbbbbbbbcbbbbccaccbcc.
	rule cbbb -> aacc at position 11
.aacbbbbbbbbaaccbccaccbcc.
	rule a -> bb at position 11
.aacbbbbbbbbbbaccbccaccbcc.
	rule a -> bb at position 13
.aacbbbbbbbbbbbbccbccaccbcc.