Constant KOALABEAR_POSEIDON2_RC_16_EXTERNAL_INITIAL 

pub const KOALABEAR_POSEIDON2_RC_16_EXTERNAL_INITIAL: [[KoalaBear; 16]; 4];

Round constants for width-16 Poseidon2 on KoalaBear.

Generated by the Grain LFSR with parameters: field_type=1, alpha=3 (exp_flag=0), n=31, t=16, R_F=8, R_P=20

Generated by poseidon2/generate_constants.py --field koalabear --width 16.

Layout: external_initial (4 rounds × 16 elements).