I took the index with the words, transformed the range to binary, included 3 zeros, calculated the sha256 digest, took the main Section of the hexadecimal to transform it to binary, extra 3 zeros for the 8 digits of your binary and acquired 00000010011 which translates to 19 in decimal. https://tbookmark.com/story18709057/5-essential-elements-for-bip39-explained