I took the index of your words, transformed the quantity to binary, included a few zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, additional three zeros towards the 8 digits from the binary and received 00000010011 which interprets to 19 in https://advicebookmarks.com/story27213437/a-secret-weapon-for-bip39-words-to-numbers