(Geller, 1965) created this structure under pressures of about 35 kBar, but works such as (Villars, 2018) list it as the room temperature structure for In$_{3}$Te$_{4}$.
In$_{3}$Te$_{4}$ and Sn$_{4}$P$_{3}$ have the same AFLOW prototype label, A3B4_hR7_166_ac_2c. They are generated by the same symmetry operations with different sets of parameters (--params) specified in their corresponding CIF files.
Hexagonal settings of this structure can be obtained with the option --hex.
S. Geller, A. jayaraman, and J. G. W. Hull, Crystal chemistry and superconductivity of pressure-induced phases in the In-Te system, J. Phys. Chem. Solids 26, 353–361 (1965), doi:10.1016/0022-3697(65)90164-2.
G. Han, Z.-G. Chen, C. Sun, L. Yang, L. Cheng, Z. Li, W. Lu, Z. M. Gibbs, G. J. Snyder, K. Jack, J. Drennan, and J. Zou, A new crystal: layer-structured rhombohedral In$_{3}$Se$_{4}$, CrystEngComm 16, 393–398 (2014), doi:10.1039/c3ce41815d.
First cited in
H. Eckert, S. Divilov, M. J. Mehl, D. Hicks, A. C. Zettel, M. Esters, X. Campilongo, and S. Curtarolo, The AFLOW Library of Crystallographic Prototypes: Part 4, Comp. Mat. Sci. 240, 112988 (2024). (doi=10.1016/j.commatsci.2021.110450)