I took the index in the words, transformed the number to binary, added three zeros, calculated the sha256 digest, took the very first Element of the hexadecimal to transform it to binary, additional three zeros for the 8 digits on the binary and obtained 00000010011 which interprets to 19 in https://bookmarkinglive.com/story19845426/getting-my-bip39-words-to-numbers-to-work