rbafn brafn rabfn arbfn barfn abrfn rbfan brfan rfban frban bfran fbran rafbn arfbn rfabn frabn afrbn farbn bafrn abfrn bfarn fbarn afbrn fabrn rbanf branf rabnf arbnf barnf abrnf rbnaf brnaf rnbaf nrbaf bnraf nbraf ranbf arnbf rnabf nrabf anrbf narbf banrf abnrf bnarf nbarf anbrf nabrf rbfna brfna rfbna frbna bfrna fbrna rbnfa brnfa rnbfa nrbfa bnrfa nbrfa rfnba frnba rnfba nrfba fnrba nfrba bfnra fbnra bnfra nbfra fnbra nfbra rafnb arfnb rfanb franb afrnb farnb ranfb arnfb rnafb nrafb anrfb narfb rfnab frnab rnfab nrfab fnrab nfrab afnrb fanrb anfrb nafrb fnarb nfarb bafnr abfnr bfanr fbanr afbnr fabnr banfr abnfr bnafr nbafr anbfr nabfr bfnar fbnar bnfar nbfar fnbar nfbar afnbr fanbr anfbr nafbr fnabr nfabr
Note: these 'words' (valid or invalid) are all the permutations of the word rbafn. These words are obtained by scrambling the letters in rbafn.