Between each pair of terms in this sequence is the amount the sequence is decreasing by. The 𝒏th term refers to a term's position in the sequence, for example, the first term has 𝒏 = 1, the second ...

The gentians (Gentianaceae, Asteridae) form a morphologically and ecologically diverse group of plants with interesting phytochemical and medicinal properties. The family contains six tribes, but ...