111111121

Appears in sequences

• a(1) = 1, then the smallest number not included earlier and not a string of 1's such that the concatenation a(n), a(n+1) is a palindrome.at n=25A083122
• a(n) is the smallest integer that contains a(n-1) but does not begin with a(n-1).at n=8A179956
• Composite numbers whose product of digits is 2.at n=30A201015