I took the index on the words, transformed the number to binary, extra three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to convert it to binary, included three zeros to your 8 digits on the binary and bought 00000010011 which translates to 19 in decimal. https://ez-bookmarking.com/story19116079/ledger-seed-phrase-bip39-no-further-a-mystery