19999999

Properties

Appears in sequences

• Smallest prime containing exactly n 9's.at n=7A037071
• Primes of the form 1999...999.at n=4A055558
• a(n) is the smallest number k such that the letter "N" appears n times when k is written in English.at n=18A060227
• Smallest number whose sum of digits is n^2.at n=8A061104
• Smallest number whose sum of digits is n^3.at n=4A061105
• Smallest prime ending in exactly n 9's.at n=6A065582
• a(n) = 2*10^(n-1) - 1.at n=7A067272
• Smallest prime with sum of digits = 2^n.at n=5A067522
• Smaller of two consecutive primes which have no common digits.at n=28A068803
• Number of palindromes of length <= n.at n=13A070199
• Smallest prime whose digital sum is equal to the n-th composite number, or 0 if no such prime exists.at n=44A073867
• Primes of the form 2^r*5^s - 1.at n=32A077313
• Smallest prime == 1 (mod n-th unary number U(n) = (10^n-1)/9).at n=6A083808
• Smallest prime whose product of digits is 3^n.at n=14A088653
• Primes of the form identical digits preceded by a 1.at n=8A090149
• Triangle T(n,k) = 10^(n-1) -1 + k*floor(9*10^(n-1)/(n+1)), with 1 <= r <= n, read by rows.at n=28A093850
• a(n) = A002283(n-1) + floor(A052268(n)/(1+n)).at n=7A093851
• Primes with digit sum = 64.at n=0A107618
• Smallest prime whose digital sum is equal to the n-th composite number not congruent to 0 (modulo 3).at n=24A111380
• Smallest prime of the form 1 followed by n copies of k.at n=6A112733