The orders of nonsingular derivations of Lie algebras of characteristic   two
  Nonsingular derivations of modular Lie algebras which have finite multiplicative order play a role in the coclass theory for pro-$p$ groups and Lie algebras. A study of the set N_p of positive integers which occur as orders of nonsingular derivations of finite-dimensional non-nilpotent Lie algebras of positive characteristic p was initiated by Shalev and continued by the present author. In this paper we continue this study in the case of characteristic two. Among other results, we prove that any divisor n of 2^k-1 with $n^4>(2^k-n)^{3}$ belongs to N_2. Our methods consist of elementary arguments with polynomials over finite fields and a little character theory of finite groups. 
Sandro Mattarei