278545

Appears in sequences

• Carmichael numbers: composite numbers k such that a^(k-1) == 1 (mod k) for every a coprime to k.at n=23A002997
• Expansion of (1+2*x-3*x^2-4*x^3+x^4)/(1-8*x^2+11*x^4).at n=14A033482
• Carmichael numbers with exactly 4 prime factors.at n=8A074379
• Pseudoprimes to bases 2 and 7.at n=17A083733
• Pseudoprimes to bases 3 and 7.at n=21A083735
• Pseudoprimes to bases 2,3 and 7.at n=12A083738
• Carmichael numbers C such that C-1 is not a Niven/Harshad number.at n=4A097061
• Devaraj numbers: squarefree r-prime-factor (r>1) integers N=p1*...*pr such that phi(N)=(p1-1)*...*(pr-1) divides gcd(p1-1,...,pr-1)^2*(N-1)^(r-2).at n=26A104016
• Pseudoprimes (base-2) equal to product of 4 primes not necessarily distinct.at n=21A112441
• a(n) is the smallest Carmichael number (A002997) divisible by the n-th prime, or 0 if no such number exists.at n=28A135721
• Carmichael numbers with more than 3 prime factors.at n=8A141711
• Odd composite numbers m for which A000111(m) == (-1)^( (m-1)/2 ) (mod m).at n=34A180942
• Carmichael numbers divisible by 17 and 29.at n=1A182381
• Carmichael numbers n such that A002322(n) = 2^k * p, where k is an integer and p is a prime.at n=3A214428
• Carmichael numbers divisible by a smaller Carmichael number.at n=4A214758
• Pseudoprimes divisible by a smaller pseudoprime.at n=20A215150
• Fermat pseudoprimes to base 2 divisible by 5.at n=22A216023
• Composite integers k such that 2^k == 2 (mod k*(k+1)).at n=32A217465
• Carmichael numbers (A002997) that are not absolute Euler pseudoprimes (A033181).at n=15A262043
• Carmichael numbers k such that the odd part of k-1 is squarefree.at n=6A263403