[@leb_true_to_le //
|>commutative_times in ⊢ (??%); > times_exp
@(transitive_le ? (exp n 2))
- [<associative_times >exp_2 in ⊢ (??%); @le_times //
+ [<associative_times >exp_2 in ⊢ (??%); @le_times [@le18|//]
|@(le_exp1 … (lt_O_S ?))
@(le_plus_to_le 3)
cut (3+2*n/3*3 = S(2*n/3)*3) [//] #eq1 >eq1