I took the index from the words, transformed the range to binary, included 3 zeros, calculated the sha256 digest, took the main Element of the hexadecimal to transform it to binary, included three zeros to your eight digits with the binary and bought 00000010011 which interprets to 19 in decimal. https://bookmarkplaces.com/story18745088/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator