126217

Appears in sequences

• Carmichael numbers: composite numbers k such that a^(k-1) == 1 (mod k) for every a coprime to k.at n=18A002997
• Composite numbers k such that k == +-1 (mod 8) and 2^((k-1)/2) == 1 (mod k).at n=33A006971
• Strong pseudoprimes to base 74.at n=32A020300
• Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 2,1.at n=5A037494
• Pseudoprimes to both base 2 and base 3, i.e., intersection of A001567 and A005935.at n=27A052155
• Carmichael numbers with exactly 4 prime factors.at n=5A074379
• Pseudoprimes to bases 2 and 5.at n=19A083732
• Pseudoprimes to bases 3 and 5.at n=17A083734
• Pseudoprimes to bases 2, 3 and 5.at n=13A083737
• 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=21A104016
• Pseudoprimes (base-2) equal to product of 4 primes not necessarily distinct.at n=12A112441
• Nonprime numbers k such that k divides 3^((k+1)/2) - 2^((k+1)/2) - 1.at n=20A130062
• Carmichael numbers with more than 3 prime factors.at n=5A141711
• Odd composite numbers m for which A000111(m) == (-1)^( (m-1)/2 ) (mod m).at n=24A180942
• Carmichael numbers of the form C = p*(2p-1)*(n*(2p-2)+p), where p and 2p-1 are prime numbers.at n=5A182207
• Carmichael numbers divisible by 7.at n=9A182208
• Carmichael numbers divisible by 1729.at n=2A212920
• Carmichael numbers divisible by a smaller Carmichael number.at n=1A214758
• Pseudoprimes divisible by a smaller pseudoprime.at n=8A215150
• Carmichael numbers of the form (6*k + 1)*(24*k + 1)*(30*k + 1).at n=0A230722