40123

Properties

Appears in sequences

• Number of subsets of { 1, ..., n } containing an A.P. of length 9.at n=21A018794
• Numbers k such that 171*2^k-1 is prime.at n=36A050837
• Numbers k such that prime(k) == 1 (mod sigma(k)).at n=15A067697
• Primes whose digits can be arranged in increasing cyclic order - to form a substring of 123456789012345678901234567890...at n=46A068710
• Polynomial (1/3)*n^3 + (9/2)*n^2 + (85/6)*n - 2.at n=45A073775
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=11A074811
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=17A074811
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=19A074811
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=27A074811
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=31A074811
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=43A074811
• Least k such that prime(k) >= k*tau(k*n) where tau = A000005.at n=44A074811
• Five-digit primes which use each of the decimal digits 0 through 4 exactly once.at n=9A109176
• Numbers k such that prime(k) == 13 (mod k).at n=15A116658
• Primes formed by rearranging five consecutive decimal digits (avoiding leading 0).at n=12A156119
• Primes whose digits can be arranged as consecutive digits (more precisely, to form a substring of 0123456789).at n=33A177119
• Primes whose digits are a permutation of (0, ..., m) for some m.at n=9A187796
• Let an integer with k+1 digits as n = d(k)*10^k + d(k-1)*10^(k-1) + ... + d(0)*10^0 and consider the transform T(n) = k*10^d(k) + (k-1)*10^d(k-1) + ... + 0*10^d(0). a(n) gives the fixed points of the transform T(n).at n=31A226767
• Least positive integer m with pi(m*n) = phi(m), where pi(.) is the prime-counting function and phi(.) is Euler's totient function.at n=11A247601
• Integers x such that [f(0), f(f(0)), ..., f(...f(0)...)] is a permutation of [0, 1, ..., k-1], where k is the number of digits in x and f(a) denotes the 0-based index of the first occurrence of the substring a in x.at n=28A307620