I took the index of your words, transformed the quantity to binary, included 3 zeros, calculated the sha256 digest, took the very first Section of the hexadecimal to transform it to binary, included three zeros towards the 8 digits from the binary and received 00000010011 which interprets to 19 in https://canvas.instructure.com/eportfolios/3396498/ricardooxtv236/opening-the-world-of-bip39-a-comprehensive-overview-to-mnemonic-expressions-and-word-checklists