666667

Properties

Appears in sequences

• Primes that contain digits 6 and 7 only.at n=6A020469
• Primes that when squared gives numbers with digits in nondecreasing order.at n=21A028865
• a(n)^2 is smallest square starting with a string of n 4's.at n=5A034984
• Smallest n-digit prime containing only the digits 6 and 7, or 0 if no such prime exists.at n=5A036948
• Smallest prime containing exactly n 6's.at n=5A037065
• Find smallest pair (x,y) such that x^2-y^2 = 11...1 (n times) = (10^n-1)/9; sequence gives value of y.at n=17A048612
• Numbers k such that k^2 contains only digits {4,8,9}.at n=11A053966
• Smallest prime beginning with exactly n 6's.at n=5A065589
• Number of Fibonacci numbers A000045(k), k <= 10^n, which end in 4.at n=7A067275
• Duplicate of A067275.at n=7A073552
• Numbers k with the property that k divides one of the concatenations (k-1)(k-2) or (k-2)(k-1).at n=25A077292
• Smallest prime == 1 (mod n-th unary number U(n) = (10^n-1)/9).at n=5A083808
• Numbers n > 2 such that n divides the concatenation of n-2 and n-1.at n=6A088797
• Primes of the form identical digits followed by a 7.at n=18A090147
• a(n) = (n*10^n - n + 9)/9.at n=6A091693
• Primes of the form 60*R_k + 7, where R_k is the repunit (A002275) of length k.at n=2A093170
• Centered hexamorphic numbers: the k-th centered hexagonal number, 3k(k-1)+1, ends in k.at n=28A094534
• Euler-phi of these numbers is a decimal repdigit.at n=45A096503
• Primes of the form 1 + repdigit. Primes whose totient is a repdigit.at n=7A096505
• a(n) is the least prime following A002280[n] repdigits.at n=6A099660