5615659951domain: NAppears in sequencesCarmichael numbers that are not of the form x^2 + y^2 + z^2 where x, y and z are integers.at n=15A267462Composite numbers m such that lambda(m) = lambda(D_{m-1}), where lambda(n) is the Carmichael function of n (A002322) and D_k is the denominator (A027642) of Bernoulli number B_k.at n=0A343979