It's seems really odd, but with the launch of Canon's new 40mm f2.8, two Pancake AF tessar primes have been launched in just a few months, the being Pentax's razor thin 40mm f2.8 K-mount kit lens for their new mirrorless. Before that, the last time a similar tessar pancake was launched was Nikon's manual focus 45mm f2.8 Ai-P lens. These lenses have a simple optical design that yields excellent sharpness.
I have a Nikkor 45mm f2.8 GN, a tessar from the late 1960's that has had an Ai conversion. This lens is also excellent, and interestingly, for me, it gets most of its use as a copy lens for film negatives, used with a PB-5 bellows. It is the only lens that I could get to work consistently well with this set up. The other interesting thing about this lens is it has markings for flash guide numbers, hence the GN name.