I took the index in the words, converted the variety to binary, added 3 zeros, calculated the sha256 digest, took the main Element of the hexadecimal to transform it to binary, included 3 zeros to your eight digits of your binary and received 00000010011 which translates to 19 in decimal. https://free-bookmarking.com/story19673733/new-step-by-step-map-for-bip39-english-words