I took the index from the words, transformed the range to binary, extra a few zeros, calculated the sha256 digest, took the first Element of the hexadecimal to convert it to binary, included three zeros into the eight digits of the binary and got 00000010011 which translates to 19 in https://hyperbookmarks.com/story18798567/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator