208969201domain: NAppears in sequencesCarmichael numbers (A002997) that are the sum of three consecutive primes.at n=13A270267Numbers k such that both k and (k+1)/2 are Fermat pseudoprimes to base 2 (A001567).at n=3A303531Lesser of 2 consecutive Fermat pseudoprimes to base 2 with no prime numbers in between them.at n=4A335326