84419

Appears in sequences

• Composite numbers k that divide Fibonacci(k+1).at n=31A069107
• Numbers k that divide Fibonacci(k+1) but do not divide Fibonacci(k) + 1.at n=27A094412
• Composite numbers k that divide both Fibonacci(k+1) and Fibonacci(2k+1)-1.at n=30A182504
• Composite numbers for which the root mean square of proper divisors is an integer.at n=39A247135
• Composite squarefree numbers k such that k^2-1 is divisible by p-1 and p+1, where p are all the prime factors of k.at n=8A306685
• Chebyshev pseudoprimes to both base 2 and base 3: composite numbers k such that T(k, 2) == 2 (mod k) and T(k, 3) == 3 (mod k), where T(k, x) is the k-th Chebyshev polynomial of the first kind.at n=9A330208
• Composite squarefree numbers k such that for any prime p dividing k both (p-1)/2 and (p+1)/2 divide k+1.at n=2A392557