I took the index with the words, transformed the quantity to binary, extra 3 zeros, calculated the sha256 digest, took the main Section of the hexadecimal to transform it to binary, extra a few zeros into the 8 digits with the binary and got 00000010011 which translates to 19 in https://socialfactories.com/story5093663/5-essential-elements-for-bip39-explained