Theorem fmtno1prm

Description: The 1 st Fermat number is a prime (_second Fermat prime_). (Contributed by AV, 13-Jun-2021)

	Ref	Expression
Assertion	fmtno1prm	$$⊢\mathrm{FermatNo}\left(1\right)\in \mathbb{P}$$

Proof

Step	Hyp	Ref	Expression
1		fmtno1	$$⊢\mathrm{FermatNo}\left(1\right)=5$$
2		5prm	$$⊢5\in \mathbb{P}$$
3	1 2	eqeltri	$$⊢\mathrm{FermatNo}\left(1\right)\in \mathbb{P}$$