I took the index from the words, transformed the quantity to binary, extra a few zeros, calculated the sha256 digest, took the initial Element of the hexadecimal to convert it to binary, added a few zeros for the 8 digits from the binary and got 00000010011 which interprets to 19 https://keybookmarks.com/story19507416/ledger-seed-phrase-bip39-no-further-a-mystery