Hello SeqFans, a(n) is the smallest unused integer so far in S that has no digit dividing a(n-1); a(1)=1 S = 1,2,3,4,5,6,7,8,9,20,30,40,33,22,43,23,24,50,34,35,26,55,27,... (hope this is not old hat) Best, É.