Class 51 needs to plant 30 saplings in the open space of the school, requiring the same number of saplings in each row (plant at least 2 rows, and at least 2 trees in each row), how many different planting methods are there? Please list them.
五1班要在学校的空地上栽30棵树苗，要求每行的棵数相同(至少栽2行，每行至少栽2棵)，有几种不同的栽法？请列举出来．
<result>6</result>