I took the index of your words, transformed the selection to binary, additional a few zeros, calculated the sha256 digest, took the initial Section of the hexadecimal to transform it to binary, included 3 zeros into the 8 digits with the binary and obtained 00000010011 which translates to 19 in https://bookmarkity.com/story18882387/5-simple-techniques-for-bip39-word-list-pdf