I took the index on the words, transformed the number to binary, additional three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to convert it to binary, extra 3 zeros on the eight digits of your binary and received 00000010011 which interprets to 19 in https://checkbookmarks.com/story4330512/a-review-of-bip39-passphrase