I took the index of your words, transformed the selection to binary, added three zeros, calculated the sha256 digest, took the initial Portion of the hexadecimal to convert it to binary, added three zeros to the eight digits on the binary and obtained 00000010011 which interprets to 19 in decimal. https://thesocialroi.com/story8687491/considerations-to-know-about-bip39-word-list-pdf