I took the index in the words, transformed the variety to binary, included 3 zeros, calculated the sha256 digest, took the main Portion of the hexadecimal to convert it to binary, included three zeros to the 8 digits of your binary and received 00000010011 which interprets to 19 in decimal. https://sound-social.com/story8830669/5-simple-techniques-for-bip39-word-list-pdf