I took the index with the words, converted the selection to binary, additional three zeros, calculated the sha256 digest, took the first Component of the hexadecimal to transform it to binary, included a few zeros on the 8 digits in the binary and got 00000010011 which translates to 19 in https://thebookmarklist.com/story18749510/ledger-seed-phrase-bip39-no-further-a-mystery