A175531 Carmichael numbers of order 2.

443372888629441, 39671149333495681, 842526563598720001, 2380296518909971201, 3188618003602886401, 4208895375600667752001

Offset

1,1

Comments

Odd composite integer k is in this sequence if k == 1 or p (mod p^2 - 1) for every prime p|k.

Links

Table of n, a(n) for n=1..6.

Claude Goutier, Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22.

Everett W. Howe, Higher-order Carmichael numbers, Math. Comp. 69 (2000), 1711-1719. doi:10.1090/S0025-5718-00-01225-4

Crossrefs

Subsequence of A002997, A175530, and A299799.

Sequence in context: A261150 A181392 A299799 * A186914 A172665 A172601

Adjacent sequences: A175528 A175529 A175530 * A175532 A175533 A175534

Keyword

nonn,hard,more

Author

Max Alekseyev, Jun 08 2010

Extensions

a(6) calculated using data from Claude Goutier and added by Amiram Eldar, Apr 20 2024

Status

approved