I took the index of your words, transformed the number to binary, additional a few zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, included three zeros to your eight digits in the binary and acquired 00000010011 which translates to 19 in https://friendlybookmark.com/story19502674/a-secret-weapon-for-bip39-words-to-numbers