Fermat pseudoprime

Noun

 * 1)  With respect to an integer base b, with b > 1, a composite integer n such that bn-1 is congruent to one modulo n.
 * 341 is a Fermat pseudoprime to the base two.

Usage notes
When no base is specified, base two (binary) is usually assumed; for example, "341 is a Fermat pseudoprime to the base two" can be simplified to "341 is a Fermat pseudoprime."