919191

Appears in sequences

• Numbers whose consecutive digits differ by 8.at n=24A048410
• Integers k that divide LS(k), where LS is the "Look and Say" function (A045918).at n=37A079342
• a(n) is the least number not occurring earlier such that neighboring digits sum to 1 or 10.at n=36A182396
• List of words over {1,9} with equal numbers of 1's and 9's.at n=22A214532
• After a(1) = 1, the sequence is always extended with the smallest divisor d (not yet present in the sequence) of the last term t. If d doesn't exist, we extend the sequence with tt (t concatenated to itself). If tt doesn't produce a new d, we extend the sequence with ttt, etc. See the Comments section for more details.at n=38A348871