I took the index with the words, converted the amount to binary, added three zeros, calculated the sha256 digest, took the initial Section of the hexadecimal to convert it to binary, additional 3 zeros to your 8 digits of the binary and obtained 00000010011 which interprets to 19 in decimal. https://madbookmarks.com/story19607173/ledger-seed-phrase-bip39-no-further-a-mystery