I took the index in the words, converted the variety to binary, added 3 zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, extra three zeros to your eight digits in the binary and bought 00000010011 which interprets to 19 in decimal. https://kingslists.com/story20253777/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator