I took the index from the words, converted the quantity to binary, included a few zeros, calculated the sha256 digest, took the 1st Section of the hexadecimal to transform it to binary, additional three zeros to your 8 digits of your binary and obtained 00000010011 which interprets to 19 in https://thebookmarkage.com/story19122259/a-secret-weapon-for-bip39-words-to-numbers