I took the index in the words, transformed the quantity to binary, added 3 zeros, calculated the sha256 digest, took the first Section of the hexadecimal to transform it to binary, additional 3 zeros to the 8 digits of your binary and received 00000010011 which interprets to 19 in decimal. https://ok-social.com/story4518239/the-5-second-trick-for-ledger-seed-phrase-bip39