hurbn uhrbn hrubn rhubn urhbn ruhbn hubrn uhbrn hburn bhurn ubhrn buhrn hrbun rhbun hbrun bhrun rbhun brhun urbhn rubhn ubrhn burhn rbuhn bruhn hurnb uhrnb hrunb rhunb urhnb ruhnb hunrb uhnrb hnurb nhurb unhrb nuhrb hrnub rhnub hnrub nhrub rnhub nrhub urnhb runhb unrhb nurhb rnuhb nruhb hubnr uhbnr hbunr bhunr ubhnr buhnr hunbr uhnbr hnubr nhubr unhbr nuhbr hbnur bhnur hnbur nhbur bnhur nbhur ubnhr bunhr unbhr nubhr bnuhr nbuhr hrbnu rhbnu hbrnu bhrnu rbhnu brhnu hrnbu rhnbu hnrbu nhrbu rnhbu nrhbu hbnru bhnru hnbru nhbru bnhru nbhru rbnhu brnhu rnbhu nrbhu bnrhu nbrhu urbnh rubnh ubrnh burnh rbunh brunh urnbh runbh unrbh nurbh rnubh nrubh ubnrh bunrh unbrh nubrh bnurh nburh rbnuh brnuh rnbuh nrbuh bnruh nbruh
Note: these 'words' (valid or invalid) are all the permutations of the word hurbn. These words are obtained by scrambling the letters in hurbn.