Ich erinnere mich, den Herrn schon einmal gesehen zu haben.

English Translation

I remember seeing the gentleman before.

Is “Herrn” actually a word? Shouldn’t it be “Herren”?

No, “Herrn” is right here, It’s irregular.
Sg, Gen, Dat, Akk. = “Herrn” (here: Akk.)
Pl. “Herren”

More details and examples:

3 Likes

I’ve heard “Meine Damen und Herren” of course, but I don’t think I’ve ever heard “Herrn” before (or if I did, my brain chose to hear it as “Herren”). This is good to know, thank you.