11921001

Appears in sequences

• Carmichael numbers that are not == 1 mod 12. There are 69 Carmichael numbers out to 2*m+1, m=2*10^6 and all but the above 9 are 1 mod 12.at n=12A110889
• Carmichael numbers not congruent to 1 modulo 6.at n=7A205947
• 3*n*(9n + 2)*(18n - 1), where n runs through the odd numbers 1, 3, 5,...at n=14A213071
• Least Carmichael number that is divisible by the n-th cyclic number A003277(n), or 0 if no such number exists.at n=30A253595
• Carmichael numbers divisible by 3.at n=3A258801
• Carmichael numbers (A002997) that are the sum of three consecutive primes.at n=6A270267
• Carmichael numbers k for which A053575(k) [the odd part of phi] divides k-1.at n=17A339869
• Intersection of A137409 and A339870: Composite numbers k of the form 4u+1 having more than one prime factor of type 4u+3, and for which the odd part of phi(k) divides k-1.at n=30A339875
• The lesser of twin Carmichael numbers: a pair of consecutive Carmichael numbers (A002997) without a non-prime-power weak Carmichael number (A087442) between them.at n=17A365022