243221domain: NAppears in sequencesNumber of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 283", based on the 5-celled von Neumann neighborhood.at n=8A271118A "look-and-say" sequence. Describe the previous term by overstating the digit count by 1. a(1) = 1.at n=4A359223