I took the index with the words, converted the amount to binary, included a few zeros, calculated the sha256 digest, took the main Section of the hexadecimal to transform it to binary, additional 3 zeros into the 8 digits of the binary and got 00000010011 which translates to 19 in https://ok-social.com/story4387080/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting