181841domain: NAppears in sequencesEuler transform of A027656(n-1).at n=39A035528A000012 * A122890.at n=52A135722Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 581", based on the 5-celled von Neumann neighborhood.at n=8A273070