121111

Appears in sequences

• Numbers n such that sum of digits and product of digits are both prime.at n=30A052430
• Leftmost 1 is converted to a 2, which then propagates one step at a time until it is rightmost; then it changes to a pair of 1's and the process repeats.at n=23A071762
• 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=16A083122
• Let f(n) be the number of sequences of 1's and 2's which sum to n. Sequence contains the string of sequences.at n=50A114034
• Zero-free numbers with digit sum equal to 7.at n=61A119461
• Least early bird number of order n.at n=12A133652
• Numbers with digital product = 2.at n=19A199986
• Composite numbers whose product of digits is 2.at n=13A201015
• Triangle read by rows in which row n lists the binary words of length n over the alphabet {1,2} with no initial repeats.at n=26A211029
• Composite numbers for which both sum and product of digits are primes.at n=13A225864
• Elements of the Motzkin words sub-operad Motz of TN generated by 00 and 010.at n=26A231872
• a(n) = concatenation of decimal expansions of powers of 11 (in decreasing order).at n=2A242645
• Partial sums of A255744.at n=39A255765
• Consider the Post tag system described in A284116 (but adapted to the alphabet {1,2}) ; sequence lists the words that terminate in the empty word.at n=40A289675
• a(1) = 1; a(2) = 2; for n > 2, a(n) is the least number > a(n-1) whose decimal representation is uniquely the concatenation of the decimal representations of two distinct earlier terms.at n=35A336528