An explicit counterexample, of n = 906,180,359 was given by R. Sherman Lehman in 1960; the smallest counterexample is n = 906,150,257, found by Minoru Tanaka in 1980.
Ein erstes explizites Gegenbeispiel, nämlich n = 906.180.359 {\displaystyle n=906.180.359} gab 1960 R. Sherman Lehman an; das tatsächlich kleinste Gegenbeispiel n = 906.150.257 {\displaystyle n=906.150.257} fand Minoru Tanaka 1980.