I took the index of the words, transformed the number to binary, extra a few zeros, calculated the sha256 digest, took the initial Element of the hexadecimal to transform it to binary, extra three zeros towards the eight digits with the binary and obtained 00000010011 which translates to 19 in https://pr1bookmarks.com/story19138243/ledger-seed-phrase-bip39-no-further-a-mystery