I took the index on the words, transformed the range to binary, extra a few zeros, calculated the sha256 digest, took the main Element of the hexadecimal to convert it to binary, additional three zeros towards the eight digits from the binary and got 00000010011 which translates to 19 in https://thebookmarkage.com/story18928810/5-simple-techniques-for-bip39-word-list-pdf