I took the index of the words, transformed the number to binary, added three zeros, calculated the sha256 digest, took the very first Portion of the hexadecimal to convert it to binary, included three zeros on the eight digits in the binary and obtained 00000010011 which translates to 19 in https://mnobookmarks.com/story18738299/facts-about-bip39-seed-phrase-word-list-revealed