I took the index with the words, converted the range to binary, included three zeros, calculated the sha256 digest, took the 1st Portion of the hexadecimal to transform it to binary, added 3 zeros on the eight digits from the binary and obtained 00000010011 which translates to 19 in decimal. https://baidubookmark.com/story18892199/the-basic-principles-of-bip39-passphrase-generator