MF3 equiv to 30mm APS-C lens?

I'm excited to move from Nikon DX world (D300) to MF3 (GH3, waiting for delivery). On my Nikon I love my Sigma 30mm f/1.4 EX DC HSM prime (a lens made for APS-C cameras) and I want to maintain that particular field of view for photographs.

Which native M43 lens (i.e. which focal length) on the GH3 would produce an equivalent framing/composition? I.e. which lens/mm, if I lay a photo of it over a photo from my D300/Sigma 30mm taken at same position, would match closest? The Panny 20mm? 25mm? Other?

(I've read numerous threads trying to explain FOV and DOF conversions between formats and I'm not a math person--just wondering which mm-size lens to seek out.)

Thanks.