Constant BABYBEAR_POSEIDON2_RC_16_EXTERNAL_INITIAL 

pub const BABYBEAR_POSEIDON2_RC_16_EXTERNAL_INITIAL: [[BabyBear; 16]; 4];

Round constants for width-16 Poseidon2 on BabyBear.

Generated by the Grain LFSR with parameters: field_type=1, alpha=7 (exp_flag=0), n=31, t=16, R_F=8, R_P=13

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

Layout: external_initial (4 rounds × 16 elements).