brens rbens berns ebrns rebns erbns brnes rbnes bnres nbres rnbes nrbes benrs ebnrs bners nbers enbrs nebrs renbs ernbs rnebs nrebs enrbs nerbs bresn rbesn bersn ebrsn rebsn erbsn brsen rbsen bsren sbren rsben srben besrn ebsrn bsern sbern esbrn sebrn resbn ersbn rsebn srebn esrbn serbn brnse rbnse bnrse nbrse rnbse nrbse brsne rbsne bsrne sbrne rsbne srbne bnsre nbsre bsnre sbnre nsbre snbre rnsbe nrsbe rsnbe srnbe nsrbe snrbe bensr ebnsr bnesr nbesr enbsr nebsr besnr ebsnr bsenr sbenr esbnr sebnr bnser nbser bsner sbner nsber snber ensbr nesbr esnbr senbr nsebr snebr rensb ernsb rnesb nresb enrsb nersb resnb ersnb rsenb srenb esrnb sernb rnseb nrseb rsneb srneb nsreb snreb ensrb nesrb esnrb senrb nserb snerb
Note: these 'words' (valid or invalid) are all the permutations of the word brens. These words are obtained by scrambling the letters in brens.