Sₙ₊₁ is Lₙ = ⅔(1 + √2)2n - ⅓(2 - √2)2⁻ⁿ : https://pnrtscr.com/4ci90a

⣴⣿⣦⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣿⣿⠂⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣴⣿⣿⣀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⢠⣾⣿⣿⣿⣿⣿⣿⣦⠀
⠀⠀⠀⠀⠀⠀⣴⣿⢿⣷⠒⠲⣾⣾⣿⣿
⠀⠀⠀⠀⣴⣿⠟⠁⠀⢿⣿⠁⣿⣿⣿⠻⣿⣄⠀⠀⠀⠀
⠀⠀⣠⡾⠟⠁⠀⠀⠀⢸⣿⣸⣿⣿⣿⣆⠙⢿⣷⡀⠀⠀
⣰⡿⠋⠀⠀⠀⠀⠀⠀⢸⣿⣿⣿⣿⣿⣿⠀⠀⠉⠻⣿⡀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⣿⣿⣿⣿⣿⣿⣆⠂⠀
⠀⠀⠀⠀⠀⠀⠀⠀⣼⣿⣿⣿⡿⣿⣿⣿⣿⡄⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⢠⣿⣿⠿⠟⠀⠀⠻⣿⣿⡇⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⢀⣾⡿⠃⠀⠀⠀⠀⠀⠘⢿⣿⡀⠀⠀⠀
⠀⠀⠀⠀⠀⣰⣿⡟⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⣷⡀⠀⠀
⠀⠀⠀⠀⢠⣿⠟⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠻⣿⣧⠀⠀
⠀⠀⠀⢀⣿⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⣿⣆⠀
⠀⠀⠠⢾⠇⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⣷⡤.