One per generation is a 44-cell double tubstretcher that grows by exactly 1 cell per generation. It was created by Nicolay Beluchenko in September 2005 based on his tubstretcher modification of crab and a lightweight spaceship. It was made one cell smaller by David Bell.
In July 2019, Chris Cain assembled a pattern based on one per generation, with the additional feature that from generation 47 on, its population count is exactly equal to its generation count:
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