I took the index in the words, converted the selection to binary, included 3 zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to convert it to binary, extra three zeros to your eight digits of your binary and received 00000010011 which translates to 19 in decimal. https://bookmarkloves.com/story21049700/bip39-phrase-generator-can-be-fun-for-anyone