e-one eeeee eepee enone enope enpo enzen epeen epene epone exene exxon n-p-n neez neeze nenno neope neppe nexen nexoe nexon nnooo no-no no-op nonne nonno nonop noone nooze nopep noppe noxon nozno nozze oeno- oenoe oeppo one-x onene oneno oneon oneop onne- onnen onone onoon onpop onxeo ooooo openx opepe opone oppon ozen- oznoz ozon- ozone ozono p-n-p p-o-x peene pene- penex penne penon peone pepee pepon peppe pneo- po-on po-po ponne ponzo poope poopo popex popon popop poppe poppo poxon pozzo pppox pzone x-one xeno- xenon xepon xexex xonox xoxox zenne zeno- zenpo zenzo zeppo zonne zono- zoppo zzzzz