Strange. The obverse appears to be O-104... BUT: The reverse is clearly not correct. Overton even mentions the light die lines 'opposite & below end of bust'.
I was looking on mailbockaddict, but was getting a little overwhelmed by the number of 1827 die marriages. At first glance it could be a O-149, but i don't think I'm that lucky, the site says there's 3 known. I need more eyes on it.
It does look like obv. 15. Which makes 120 and 149 candidates. Edit: I don't think it's 149, AT is not joined at base.