172081

Appears in sequences

• Carmichael numbers: composite numbers k such that a^(k-1) == 1 (mod k) for every a coprime to k.at n=20A002997
• a(n) = (n+1)*(2*n+1)*(3*n+1).at n=30A011199
• Absolute Euler pseudoprimes: odd composite numbers n such that a^((n-1)/2) == +-1 (mod n) for every a coprime to n.at n=7A033181
• Pseudoprimes to both base 2 and base 3, i.e., intersection of A001567 and A005935.at n=29A052155
• Numbers k such that phi(k)/lambda(k) increases to a record value, where phi(k) is the Euler totient function (A000010) and lambda(k) is the Carmichael lambda function (A002322).at n=27A066605
• Numbers n such that A078142(n) = A078142(n+1) = A078142(n+2), where A078142(n) is the sum of the differences of the distinct prime factors p of n and the next square larger than p.at n=28A073938
• Carmichael numbers with exactly 4 prime factors.at n=6A074379
• Pseudoprimes to bases 2 and 5.at n=22A083732
• Pseudoprimes to bases 3 and 5.at n=20A083734
• Pseudoprimes to bases 2, 3 and 5.at n=15A083737
• 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=23A104016
• Pseudoprimes (base-2) equal to product of 4 primes not necessarily distinct.at n=15A112441
• Nonprime numbers k such that k divides 3^((k+1)/2) - 2^((k+1)/2) - 1.at n=22A130062
• Carmichael numbers with more than 3 prime factors.at n=6A141711
• Composite numbers n with the property that phi(n) divides (n-1)^2.at n=23A173703
• Odd composite numbers m for which A000111(m) == (-1)^( (m-1)/2 ) (mod m).at n=29A180942
• a(n) = 3*n^4 + 6*n^3 - 3*n + 1.at n=15A181475
• Carmichael numbers of the form C = (30n-p)*(60n-(2p+1))*(90n-(3p+2)), where n is a natural number and p, 2p+1, 3p+2 are all three prime numbers.at n=1A182087
• Carmichael numbers divisible by 31.at n=3A182151
• Carmichael numbers of the form C = p*(2p-1)*(n*(2p-2)+p), where p and 2p-1 are prime numbers.at n=6A182207