15247621

Appears in sequences

• Carmichael numbers which are also base-2 strong pseudoprimes.at n=11A063847
• Carmichael numbers C such that C-1 is not a Niven/Harshad number.at n=29A097061
• Strong pseudoprimes (base-2) equal to product of 3 primes not necessarily distinct.at n=23A112450
• Carmichael numbers that have only prime divisors of the form 10k+1.at n=19A212843
• Fermat pseudoprimes to base 2 that are octadecagonal.at n=13A322160
• Primary Carmichael numbers.at n=24A324316
• Odd composite numbers k such that A111076(k)^((k-1)/2) == -1 (mod k).at n=4A329538
• Odd squarefree composite numbers k such that p-1 divides k-1 and p-1 does not divide (k-1)/2 for every prime p|k.at n=9A329799
• Carmichael numbers with exactly 3 prime factors, p*q*r, such that p-1, q-1 and r-1 have an equal 2-adic valuation.at n=9A382791