Tell me the function of the inventor Leonhard Euler that starts with the letter f?
SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q11348 . ?sbj wdt:P61 wd:Q7604 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'f')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
function: Q11348 leonhard euler: Q7604