Illustration of the main nuclear i-process flow (blue line) in the layer of 1 M_⊙, [Fe/H] = −2.5 model star with the highest neutron density of N_n ≃ 5 × 10¹⁴ cm⁻³. The blue squares correspond to the nuclei included in the network, the black ones to the stable nuclei. The abundances are depicted by the red colour scale in mass fraction. The N = 82 isotones and Z = 50 isotopes are highlighted by the vertical and horizontal dotted lines, respectively.