I took the index on the words, converted the range to binary, extra a few zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, added three zeros to the eight digits with the binary and obtained 00000010011 which interprets to 19 in https://thejillist.com/story8907631/ledger-seed-phrase-bip39-no-further-a-mystery