I took the index of your 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, included a few zeros for the 8 digits on the binary and obtained 00000010011 which interprets to 19 https://socialinplace.com/story4201281/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator