This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A375322 #18 Sep 01 2024 16:50:35
%S A375322 1729,6601,10585,15841,41041,46657,658801,1461241,1615681,1857241,
%T A375322 2433601,3057601,3581761,4767841,5031181,5148001,6840001,7207201,
%U A375322 8355841,10024561,10402561,14469841,14676481,17236801,17316001,19683001,25603201,35571601,35703361,38624041
%N A375322 Carmichael numbers k such that k-1 is a Novak-Carmichael number.
%C A375322 Composite numbers k such that lambda(k) divides k-1 and lambda(k-1) divides k-1, where lambda(m) = A002322(m).
%C A375322 These are composites k such that b^(k-1) == 1 (mod (k-1)*k) for every b coprime to (k-1)*k.
%C A375322 Composites k such that B^(b^(k-1)-1) == 1 (mod k^2) for every B coprime to k and for every b coprime to (k-1)*k.
%H A375322 Amiram Eldar, <a href="/A375322/b375322.txt">Table of n, a(n) for n = 1..10000</a>
%t A375322 Select[Range[1, 10^6, 2], CompositeQ[#] && And @@ Divisible[# - 1, CarmichaelLambda[# + {-1, 0}]] &] (* _Amiram Eldar_, Aug 12 2024 *)
%o A375322 (PARI) f(n) = lcm(znstar(n)[2]); \\ A002322
%o A375322 isok(k) = !isprime(k) && !((k-1) % f(k)) && !((k-1) % f(k-1)); \\ _Michel Marcus_, Aug 13 2024
%Y A375322 Cf. A002322, A002997, A124240 (Novak-Carmichael numbers), A337119.
%K A375322 nonn
%O A375322 1,1
%A A375322 _Thomas Ordowski_, Aug 12 2024
%E A375322 More terms from _Amiram Eldar_, Aug 12 2024