Hello Math-Fun, A Marf-Low rule is coded in a 3-digit base-10 integer abc where neither a nor b = 0. A seq of integers is then produced with this rule. This abc integer is interpreted like this: a = a(1) [taken in the set 1,2,3,4,5,6,7,8,9] b = a multiplicative factor [taken in the same set] c = a stop-digit [taken in the set 1,2,3,4,5,6,7,8,9,0]. Example: the Marf-Low rule 173 produces the seq: S = 1, 7, 49, 343, 2, 14, 98, 686, 4802, 33614, 3, 4, 28, 196, 1372, 5, 35, 6, 42, 296,... Explanation: #Start the seq with a(1) = a [here a(1) = 1] #If a(n) doesn't show the stop-digit c, then a(n+1) = 7*a(n) [this is the case here, as 7, the result of 7*a(1), does not show any "3" digit] #else a(n+1) is the smallest integer not yet in the seq. [we will see this below]. The rule 173 produces indeed 1, 7, 49, 343 which stops and restarts with 2, 14, 98, 686, 4802, 33614 which stops and restarts with 3 which stops and restarts with 4, 28, 196, 1372 which stops and restarts with 5, 35 which stops, etc. Which Marf-Low rule (from 110 to 999) produces the nicest 10,000-point graph, according to you? Best, É.