Amanda By Night quickly sniffed out the answer to today's riddle:
NOSE + FUR + R2 = NOSFERATU!
So, if we stick to our equations, that means: Nosferatu (1922) + Nosferatu (1979) = TWO more movies I've not seen! That's two potential classics, both quite highly regarded from the looks of things. And if we add them to Blacula, Ingrid Pitt and Bela Lugosi's Dracula, that's one rather large pile of Very Important Vamps I've never clapped eyes on.
Sorry, Amanda, there ain't no prize but I will point you in the direction of two fantastic free commentaries for that other classic vampire movie Fright Night, one featuring director Tom Holland with William Ragsdale, Stephen Geoffreys and FX Artist Randall William Cook, and the other with Tom Holland, Chris Sarandon and Jonathan Stark. There you go: it's the gift that keeps on giving! Well, if you listen to them repeatedly.