I took the index in the words, converted the quantity to binary, added 3 zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, included three zeros to the 8 digits from the binary and obtained 00000010011 which interprets to 19 in https://bookmarkpagerank.com/story18963384/the-ultimate-guide-to-bip39-seed-phrase-github