A175531 Carmichael numbers of order 2.

443372888629441, 39671149333495681, 842526563598720001, 2380296518909971201, 3188618003602886401, 4208895375600667752001

Offset: 1

Author

Max Alekseyev, Jun 08 2010

Keywords

• nonn
• hard
• more

Comments

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

Links

• 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.

Extensions

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