22221

Appears in sequences

• Numbers whose maximal base-10 run length is 4.at n=30A033285
• k th digit of a(n) is the number of different digits within 4 of k (not including k).at n=15A039990
• Numbers having four 2's in base 10.at n=9A043500
• Rotating digits of a(n)^2 right once still yields a square.at n=18A045877
• a(n) = (2*n-1)*(n^2 -n +6)/6.at n=40A049480
• Numbers in Morse code, with 1 for a dot, 2 for a dash and 0 between digits/letters.at n=9A060109
• A064637 converted to factorial base.at n=25A064477
• Expansion of g.f. x*(1+10*x)/((1-x)*(1-10*x^2)).at n=9A094623
• Digit reversal of A096299(n).at n=23A096104
• n expressed in Fibonacci binary-like number system using only 1's and 2's.at n=18A108960
• List of pairs (n,m) with n < m such that the decimal expansion of m is a cyclic shift of that of n and m^2 is a cyclic shift of n^2.at n=9A134514
• Second elements of the pairs listed in A134514.at n=4A134585
• a(n) = (2*10^n - 11)/9.at n=4A165402
• a(n) is the least number such that k = n*a(n) has sum of digits n and ends with the digit string n, or 0 if no such number exists.at n=44A175690
• a(2n) = a(n), a(2n+1) = 10*a(n) + a(n+1).at n=46A178243
• "Early bird" squares: write the square numbers in a string 149162536496481100... . Sequence gives numbers k such that k^2 occurs in the string ahead of its natural place.at n=40A181585
• Numbers for which the sum of reciprocals of square of digits is an integer.at n=10A182452
• Numbers of rank 11 in the poset of lunar numbers.at n=38A191753
• List of primitive words over the alphabet {1,2}.at n=51A213969
• Shortest (x+1,2x)-code of n.at n=16A233135