231809domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes that remain prime through 4 iterations of function f(x) = 7x + 6.at n=19A023318Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 147", based on the 5-celled von Neumann neighborhood.at n=8A270291Prime numbersat n=20583