9439201

Appears in sequences

• Lucas pseudoprimes whose reversal is prime.at n=21A164824
• Carmichael numbers that have only prime divisors of the form 10k+1.at n=15A212843
• Smallest number k such that gcd(phi(k), k-1) = n * lambda(k).at n=19A284089
• Carmichael numbers k such that phi(k) divides (k-1)*lambda(k).at n=22A306338
• Carmichael numbers k for which the 2-adic valuation of phi(k) does not exceed the 2-adic valuation of k-1.at n=7A339818
• 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=30A345753
• The lesser of twin Carmichael numbers: a pair of consecutive Carmichael numbers (A002997) without a non-prime-power weak Carmichael number (A087442) between them.at n=13A365022