intuition.
exists (expnat 2 (max c 6)).
intuition.
eapply poly_lt_exp_ge_6.
eapply le_trans.
2:{
eapply H.
}
eapply Nat.pow_le_mono_r.
omega.
eapply Max.le_max_l.
eapply le_trans.
2:{
eapply H.
}
eapply Nat.pow_le_mono_r.
omega.
eapply Max.le_max_r.
Qed.

Theorem negligible_exp_den :
negligible (fun n => 1 / expnat 2 n)%rat.