6189121

Appears in sequences

• Least number for which Solovay-Strassen primality test on bases < prime(n) fails.at n=8A007324
• Denominators of continued fraction convergents to sqrt(349).at n=12A041661
• Carmichael numbers C such that C-1 is not a Niven/Harshad number.at n=20A097061
• a(n) is the smallest Carmichael number (A002997) with the n-th prime as its smallest prime divisor, or 0 if no such number exists.at n=16A135720
• a(n) is the least Carmichael number of the form prime(n)*prime(n')*prime(n") with n < n' < n", or 0 if no such number exists.at n=17A141705
• Carmichael numbers that have only prime divisors of the form 10k+1.at n=12A212843
• Carmichael numbers (A002997) that are the sum of two squares.at n=26A265237
• Carmichael numbers that are the average of two consecutive primes.at n=5A265669
• Sarrus numbers (A001567) that are the average of two consecutive primes.at n=29A265684
• Carmichael numbers whose prime factors form an arithmetic progression.at n=6A300949
• Primary Carmichael numbers.at n=15A324316
• Imprimitive Carmichael numbers: Carmichael numbers m such that if m = p_1 * p_2 * ... *p_k is the prime factorization of m then g(m) = gcd(p_1 - 1, ..., p_k - 1) > sqrt(lambda(m)), where lambda is the Carmichael lambda function (A002322).at n=9A328935
• Numbers that are both Fermat pseudoprimes to base 2 (A001567) and Bruckman-Lucas pseudoprimes (A005845).at n=28A329240
• Carmichael numbers (A002997) that are not minimal in their family.at n=5A335584
• Euler-Fibonacci pseudoprimes: odd composites k such that F(k) == 5^((k-1)/2) == +-1 (mod k), where F(k) = A000045(k), the Fibonacci numbers.at n=22A345753
• Smallest Euler-Jacobi pseudoprime to all natural bases up to prime(n) - 1 that is not a base prime(n) Euler-Jacobi pseudoprime.at n=8A354692
• Composites that cause a witness to be added to a set of Fermat witnesses: a(n) is the smallest composite number that is not guaranteed composite using Fermat's Little Theorem by the witness A380978(i) for any i < n.at n=16A380979