l e v c h u k @ l a n , k r a s u , r u i e v c h u k @ h o m e , k r a s n o y a r s k , r u
AbstractWe consider the maximal nilpotent subalgebra N~(K) of the Chevalley algebra of the type over an arbitrary field K. Our purpose is enumeration of ideals of NO(K) that are invariant under the subgroup D of all diagonal automorphisms. Connections between ideals of NO(K) and normal subgroups of the unipotent subgroup of the Chevalley group of the type • over K are used. Finally, we use methods of integral representation of sums and of listing lattice paths. We also discuss some other problems of the enumeration of ideals.