Carmichal number 561

561 is the smallest Carmichael number in the ring ofintegers. However it is only a pseudoprime in the ringof Gaussian integers. We can use pari to findthe bases to which 561 is a pseudoprime. Ifound it is pseudoprime to bases 12 + i, 22 +i,34 + i and 56 + i. Needless to say it is apseudoprime to other bases too. More on this later.