2438403661domain: NAppears in sequencesCarmichael numbers whose prime factors all have the form p=1+x^2+y^2 for some x,y in Z.at n=24A258839a(1) = 561; a(n+1) = smallest Fermat pseudoprime to all natural bases up to lpf(a(n)).at n=20A300629Records in A083876.at n=20A348258