I took the index with the words, converted the variety to binary, included three zeros, calculated the sha256 digest, took the 1st part of the hexadecimal to transform it to binary, extra three zeros on the eight digits in the binary and obtained 00000010011 which interprets to 19 in decimal. https://socialislife.com/story4268764/ledger-seed-phrase-bip39-no-further-a-mystery