req.py

import requests, os, sys

def flatten(thing):
    final = []
    for item in thing:
        final.extend(flatten(item)) if type(item) == list else final.append(item)
    return final

nums = "0123456789"
filename = "2619{}"
url = "https://nhentai.net/g/2619{}/"
buildreplace = [[str(char1)+str(char2) for char2 in nums] for char1 in nums]
buildreplace = flatten(buildreplace)
build = [(filename.format(num), url.format(num)) for num in buildreplace]

for url in build:
    file = open(os.path.join(sys.path[0], url[0]), 'w+', encoding='utf-8')
    response = requests.get(url[1])
    file.write(response.text)
    file.close()
    if 'RiceKrispieTreatsAdvertisement' in response.text:
        print(url)
    print('File Written - {}'.format(url[1]))