216197domain: NAppears in sequencesa(0) = 1. a(n+1) = sum{k=0 to n} a(n-k)*a(ceiling(k/2)).at n=17A127681Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 499", based on the 5-celled von Neumann neighborhood.at n=8A272561