I took the index from the words, transformed the range to binary, extra 3 zeros, calculated the sha256 digest, took the very first Element of the hexadecimal to transform it to binary, additional a few zeros on the 8 digits of your binary and obtained 00000010011 which interprets to 19 https://infopagex.com/story4506255/a-review-of-bip39-passphrase