The partial sums of a sequence x = x 1 , x 2 , . . . , x k of distinct non-identity elements of a group (G, •) are s 0 = id G and s j = j i=1 x i for 0 < j ≤ k. If the partial sums are all different then x is a linear sequencing and if the partial sums are all different when |i−j| ≤ t then x is a t-weak sequencing. We investigate these notions of sequenceability in semidirect products using the polynomial method. We show that every subset of order k of the non-identity elements of the dihedral group of order 2m has a linear sequencing when k ≤ 12 and either m > 3 is prime or every prime factor of m is larger than k!, unless s k is unavoidably the identity; that every subset of order k of a non-abelian group of order three times a prime has a linear sequencing when 5 < k ≤ 10, unless s k is unavoidably the identity; and that if the order of a group is pe then all sufficiently large subsets of the non-identity elements are t-weakly sequenceable when p > 3 is prime, e ≤ 3 and t ≤ 6.