from collections import Counter

def solve(nums, k):
   c = Counter(nums)
   res = []
   for n in c:
      if c[n] >= k:
         res.append(n)
   return res

nums = [2,5,6,2,6,1,3,6,3,8,2,5,9,3,5,1]
k = 3
print(solve(nums, k))

[2,5,6,2,6,1,3,6,3,8,2,5,9,3,5,1]，3

[2，5，6，3]