A346569 Carmichael numbers (A002997) k such that A003961(k) is also a Carmichael number.

938531360353681, 6178246534322281, 518705522457928921, 7019247908645553241, 16242056799655920481, 94812683932464811561, 94986212971063089241, 408133613144935002601, 418441276466266605481, 453648717063017803081, 556606627235843071681, 1140359076998537247001

Offset

1,1

Comments

Each of the first 17 terms has 3 distinct prime divisors. [updated Apr 22 2024]

a(6) <= 94812683932464811561. A term with 4 prime factors is 9584146525723596902470058833132261. - Daniel Suteu, Jul 24 2021

Links

Amiram Eldar, Table of n, a(n) for n = 1..17 (terms below 10^22 calculated using data from Claude Goutier)

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

Index entries for sequences related to Carmichael numbers.

Example

938531360353681 = 53881 * 107761 * 161641 is a term since it is a Carmichael number, and A003961(938531360353681) = 53887 * 107773 * 161659 = 938844932257009 is also a Carmichael number.

Crossrefs

Cf. A002997, A003961.

Subsequence of A346568.

Sequence in context: A173405 A104835 A128446 * A349029 A052098 A172607

Adjacent sequences: A346566 A346567 A346568 * A346570 A346571 A346572

Keyword

nonn

Author

Amiram Eldar, Jul 23 2021

Extensions

a(6) verified and a(7)-a(13) calculated using using data from Claude Goutier by Amiram Eldar, Apr 22 2024

Status

approved