AMC / AIME · Modular Arithmetic · Hard

Modular Arithmetic: Least composite math with math?

Congruences and power cycles.

Try the problem

Least composite n>1n>1 with 2n≡2(modn)2^n\equiv2\pmod n?

Hint and answer

Concept to use

CRT systems.

Hint

Pseudoprime to base 22.

Answer

341

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