When were Frederick William I of Prussia's children Wilhelmine of Prussia and Margravine of Brandenburg-Bayreuth born?
SELECT ?value WHERE { wd:Q105013 p:P40 ?s . ?s ps:P40 wd:Q237740 . ?s pq:P569 ?value}
frederick william i of prussia: Q105013 wilhelmine of prussia, margravine of brandenburg-bayreuth: Q237740