message = "abdcacau"


def generate_substrings(text, length):
    return [(i, i+length, message[i:i+length]) for i in range(len(text) - length + 1)]


def count_occurrences(text, length):
    return [(substring, text.count(substring[2])) for substring in generate_substrings(text, length)]


print(count_occurrences(message, 1))
print(count_occurrences(message, 2))
print(count_occurrences(message, 3))
print(count_occurrences(message, 4))
print(count_occurrences(message, 5))
print(count_occurrences(message, 6))
print(count_occurrences(message, 7))
print(count_occurrences(message, 8))

------

[((0, 1, 'a'), 3), ((1, 2, 'b'), 1), ((2, 3, 'd'), 1), ((3, 4, 'c'), 2), ((4, 5, 'a'), 3), ((5, 6, 'c'), 2), ((6, 7, 'a'), 3), ((7, 8, 'u'), 1)]
[((0, 2, 'ab'), 1), ((1, 3, 'bd'), 1), ((2, 4, 'dc'), 1), ((3, 5, 'ca'), 2), ((4, 6, 'ac'), 1), ((5, 7, 'ca'), 2), ((6, 8, 'au'), 1)]
[((0, 3, 'abd'), 1), ((1, 4, 'bdc'), 1), ((2, 5, 'dca'), 1), ((3, 6, 'cac'), 1), ((4, 7, 'aca'), 1), ((5, 8, 'cau'), 1)]
[((0, 4, 'abdc'), 1), ((1, 5, 'bdca'), 1), ((2, 6, 'dcac'), 1), ((3, 7, 'caca'), 1), ((4, 8, 'acau'), 1)]
[((0, 5, 'abdca'), 1), ((1, 6, 'bdcac'), 1), ((2, 7, 'dcaca'), 1), ((3, 8, 'cacau'), 1)]
[((0, 6, 'abdcac'), 1), ((1, 7, 'bdcaca'), 1), ((2, 8, 'dcacau'), 1)]
[((0, 7, 'abdcaca'), 1), ((1, 8, 'bdcacau'), 1)]
[((0, 8, 'abdcacau'), 1)]