I took the index on the words, transformed the amount to binary, included a few zeros, calculated the sha256 digest, took the primary part of the hexadecimal to transform it to binary, included three zeros into the 8 digits of your binary and received 00000010011 which interprets to 19 in https://captainbookmark.com/story19422757/the-5-second-trick-for-ledger-seed-phrase-bip39