Looks like a provincial coin of Gordian III from Viminacium in Moesia, see the entries and pictures here: http://www.wildwinds.com/coins/greece/moesia/viminacium/i.html
By chance, I have a scan of the catalogue and quickly checked the reference (AMNG 86) given in wildwinds. It's correct. The full reference would be: Die antiken Münzen Nord-Griechenlands, ed. F. Imhoof–Blumer for the Königliche Akademie der Wissenschaften, vol. 1: Dacien und Moesien, ed. Behrendt Pick, Berlin: Georg Reimer 1898, p. 36 (no. 86). The catalogue can be found online, but it's written in German. The "AN IIII" in the exergue means the coin was minted in Gordian's fourth regnal year. Pick assumes the denomination is a provincial dupondius.
