22222

Appears in sequences

• a(n) = 2*(10^n - 1)/9.at n=5A002276
• Kaprekar numbers: positive numbers n such that n = q+r and n^2 = q*10^m+r, for some m >= 1, q >= 0 and 0 <= r < 10^m, with n != 10^a, a >= 1.at n=18A006886
• Repdigit numbers, or numbers whose digits are all equal.at n=38A010785
• Numbers > 9 with all digits the same.at n=28A014181
• a(n) = dot_product(1,2,...,n)*(3,4,...,n,1,2).at n=38A026037
• Numbers using only digits 2 and 3.at n=30A032810
• Trajectory of 3 under map n->49n+1 if n odd, n->n/2 if n even.at n=7A037122
• Start with 1; for n>1, replace n with the concatenation of its prime factors in increasing order.at n=31A037276
• If n is not composite, a(n) = n followed by 1; if n is composite, a(n) = concatenation of prime factors of n.at n=32A049201
• The full list of 5-Kaprekar numbers.at n=3A053396
• Another version of the Kaprekar numbers (A006886): n such that n = q+r and n^2 = q*10^m+r, for some m >= 1, q >= 0 and 0 <= r < 10^m, with n != 10^a, a >= 1 and n an m-digit number.at n=16A053816
• Write what is described (putting a leading zero on numbers which have an odd number of digits).at n=52A056967
• Numbers in Morse code, with 1 for a dot, 2 for a dash and 0 between digits/letters.at n=0A060109
• Digital representation of m contains only either 1's or 2's (but not both 1's and 2's) and 0's, is palindromic and contains no singleton 2's, 1's or 0's.at n=7A061852
• Obtain m by omitting trailing zeros from n; a(n) = smallest multiple k*m which is a palindrome with even digits, or -1 if no such multiple exists.at n=41A061915
• Numbers n with property that every digit is a prime factor of n.at n=25A062239
• Smallest multiple k*n of n which has even digits and is a palindrome or becomes a palindrome when 0's are added on the left (e.g., 10 becomes 010, which is a palindrome).at n=41A062293
• Largest number whose digit product equals n; a(n)=0 if no such number exists, e.g., when n has a prime factor larger than 7; no digit=1 is permitted to avoid an infinite number of solutions.at n=31A068190
• Geometric mean of digits = 2 and digits are in nondecreasing order.at n=14A069512
• Repdigits (A010785) ordered by sum of digits (A007953).at n=25A070840