I took the index with the words, converted the range to binary, included three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to convert it to binary, added three zeros to your eight digits of the binary and acquired 00000010011 which translates to 19 in https://bookmarkfame.com/story18847564/facts-about-bip39-seed-phrase-word-list-revealed