N = 20 # max_num
array = [True] * N
# calculate
prim_nums_erato(array, N)
# show result
for k in range(N):
print(k, "<-", "prime" if array[k] else "composite")
0 <- prime
1 <- prime
2 <- prime
3 <- prime
4 <- composite
5 <- prime
6 <- composite
7 <- prime
8 <- composite
9 <- composite
10 <- composite
11 <- prime
12 <- composite
. . .
# OR
# lst = []
# for k in range(N):
# if array[k]:
# lst.append(k)
# print(lst)
print([i for i in range(len(array)) if array[i]]) # [0, 1, 2, 3, 5, 7, 11, 13, 17, 19]