I took the index of your words, converted the selection to binary, added three zeros, calculated the sha256 digest, took the first Element of the hexadecimal to transform it to binary, extra 3 zeros towards the 8 digits with the binary and acquired 00000010011 which translates to 19 in decimal. https://bookmarkrange.com/story20216237/5-essential-elements-for-bip39-explained