The T=2* symmetry is an nonofficial appellation, to be rigorous the capsid has a T=1 symmetry with each unit composed of a homodimer.
Icosahedric triangulation number is calculated following Caspar and Klug system
Physical principles in the construction of regular viruses
D. L. Caspar, A. Klug
Cold Spring Harb. Symp. Quant. Biol. 1962; 27: 1?24
D. L. Caspar, A. Klug
Cold Spring Harb. Symp. Quant. Biol. 1962; 27: 1?24