21111

Appears in sequences

• Numbers whose maximal base-10 run length is 4.at n=28A033285
• Numbers in Morse code, with 1 for a dot, 2 for a dash and 0 between digits/letters.at n=6A060109
• Decimal encoding of the prime factorization of n: concatenation of prime factors and exponents.at n=20A067599
• a(1) = 11 by convention; for n > 1, if n = p^a*q^b... then a(n) = concatenate(p,a,q,b,...).at n=21A068633
• Digitized partition numbers: numbers with (weakly) decreasing digits ordered by sum of their digits then by the numbers themselves.at n=28A068743
• The zero-free, right-to-left factorial walk encoding for each rooted plane tree encoded by A014486. Sequence A071155 shown with factorial expansion (A007623).at n=24A071157
• Factorial expansion of A071156.at n=36A071158
• 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=16A071762
• Numbers n such that sum of squares of even digits of n equals sum of squares of odd digits of n.at n=29A076164
• Left-to-right binary enumeration.at n=31A081242
• 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=14A083122
• Factorial expansions of the entries in A085219.at n=48A085221
• Lunar fourth powers: n*n*n*n, where * is lunar multiplication.at n=21A087051
• Digit reversal of A096299(n).at n=16A096104
• Keep only the first digit of each integer and concatenate them. The result is the concatenation of all integers of the sequence.at n=27A106000
• Numbers with digits 1 and 2 and at least one of each.at n=37A111066
• 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=30A114034
• Ternary emirpimes.at n=17A119684
• Take the base-3 representation of n, render that in decimal notation and take the base-3 representation of n again.at n=20A126135
• Concatenated indices of primes in prime factorization of n.at n=46A127668