How to generate dynamically combinations of list in python

Here you go, using combinations from itertools to pick sessions per week from 0-6:

from itertools import combinations

sessionsperweek = int(input("Enter sessions per week:"))

combins = list(combinations(range(7), sessionsperweek))
print("Your possible combinations are:")
print(combins)

Example run with 2 (since OP updated):

Enter sessions per week:2
Your possible combinations are:
[(0, 1), (0, 2), (0, 3), (0, 4), (0, 5), (0, 6), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6), (2, 3), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6), (4, 5), (4, 6), (5, 6)]

Example run:

Enter sessions per week:6
Your possible combinations are:
[(0, 1, 2, 3, 4, 5), (0, 1, 2, 3, 4, 6), (0, 1, 2, 3, 5, 6), (0, 1, 2, 4, 5, 6), (0, 1, 3, 4, 5, 6), (0, 2, 3, 4, 5, 6), (1, 2, 3, 4, 5, 6)]