This is a modular equation involving first $k$ ODD primes:
$$ 3^{5+7+11+13+17+\dotsb+p(k-3)+p(k-2)}=p(k-1) \mod p(k) $$
where $p(k)$ is the $k$-th ODD prime number.
I've checked $k$ up to $50$, but the only solution I've found is for $k=20$.
Are there any other solutions for $k$?