Help Identifying a type of Lens Mount this is?

I purchased a 70-210mm 3.5 Vivitar lens for a great deal. Unfortunatly, the mount doesn't seem to be fit for my Nikon. Can anyone help me identify this Vivitar lens mount? Is it a cannon or pentax maybe? I put a link to a picture of it below. Thank you in advance!

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Added (1). Lol it may still be a great deal if i can sell it even if i can't use it.

Added (2). I think you are right that it may be a pentax k mount. On the body of the lens it has a "P/K" on it which i believe means its a pentax k mount. I'm used do nikon lenses so this is new to me.

Not such a good deal if you can't use it.

Hmm

You will have to take it into a proper camera store to identify it since there does not seem to be any identification on the mount

Looks like a Pentax mount
http://a.img-dpreview.com/lensreviews/pentax_50_1p4_p15/page3.asp

I matched it up to a lens that I own, to the best of my ability… It looks like a Pentax K-Mount but without actually sizing it up or fitting it to camera… No-one could say for certain.

You can get cheap Pentax film bodies that would work with it if it does turn out to be a K-mount lens.