proposition: Fact z3seqE (n : nat) : z3seq n = \sum_(1 <= k < n.+1)(k%:Q ^ 3)^-1.
proof: Proof. by rewrite /z3seq /ghn3 /ghn -PoszD eq_big_int_nat /= addn1. Qed.
imports: mathcomp(all_ssreflect all_algebra) tactics bigopz harmonic_numbers seq_defs