It can be written: ジャン
ジャン /jan/ if you mean it as a name. If you mean 'January' it is 一月 /i chi ga tsu/. The word 'January' itself can be referred to in Japanese as ジャニュアリー /ja nyu a ri/.
Japanese artist and print maker is called Katsushika Hokusai.
cat paw print
"Jan" is the polish name for "John".
Jan Skene's birth name is Jan Anderes.
Jan Seybold's birth name is Jan Niebuhr.
Jan Ainley's birth name is Jan Porter.
Jan Bielicz's birth name is Jan Toltyzewski.
Jan Broberg's birth name is Jan Broberg.
Jan Arvan's birth name is Jan Arvanitas.
Jan August's birth name is Jan Auggustoff.
Jan Falk's birth name is Jan Lampkins.