I took the index on the words, transformed the number to binary, included 3 zeros, calculated the sha256 digest, took the initial part of the hexadecimal to transform it to binary, included three zeros towards the eight digits on the binary and obtained 00000010011 which interprets to 19 in decimal. https://writeablog.net/ipennywpzc/h1-b-opening-the-power-of-bip39-exactly-how-to-produce-and-use-mnemonic