I took the index in the words, transformed the range to binary, added 3 zeros, calculated the sha256 digest, took the first part of the hexadecimal to transform it to binary, added a few zeros to the 8 digits with the binary and obtained 00000010011 which translates to 19 in https://funbookmarking.com/story19012021/top-guidelines-of-bip39-word-list-pdf